diff --git a/fields/action.py b/fields/action.py
index 173b93d..e5a3dc9 100644
--- a/fields/action.py
+++ b/fields/action.py
@@ -31,7 +31,7 @@ class Action(Field):
                 label=_(field.labelId)"
            id=":formId" action=":ztool.absolute_url() + '/do'">
       <input type="hidden" name="action" value="ExecuteAppyAction"/>
-      <input type="hidden" name="objectUid" value=":zobj.UID()"/>
+      <input type="hidden" name="objectUid" value=":zobj.id"/>
       <input type="hidden" name="fieldName" value=":name"/>
       <input if="field.confirm" type="button" class="button"
          var="labelConfirm=_(field.labelId + '_confirm')"
diff --git a/fields/ref.py b/fields/ref.py
index e3e066f..45c601d 100644
--- a/fields/ref.py
+++ b/fields/ref.py
@@ -978,6 +978,7 @@ class Ref(Field):
            unlink_many, delete_many).'''
         action = rq['linkAction']
         tool = obj.getTool()
+        msg = None
         if not action.endswith('_many'):
             # "link" or "unlink"
             tied = tool.getObject(rq['targetUid'])
@@ -1012,23 +1013,25 @@ class Ref(Field):
                 # Collect this object
                 target = not isObj and tool.getObject(value) or value.o
                 targets.append(target)
-            # Perform the action on every target. Count the number of failed
-            # operations.
-            mustDelete = action == 'delete_many'
-            failed = 0
-            for target in targets:
-                if mustDelete:
-                    # Delete
-                    if target.mayDelete(): target.delete()
-                    else: failed += 1
-                else:
-                    # Link or unlink
-                    exec 'self.%sObject(obj, target)' % action.split('_')[0]
+            if not targets:
+                msg = obj.translate('action_null')
+            else:
+                # Perform the action on every target. Count the number of failed
+                # operations.
+                failed = 0
+                mustDelete = action == 'delete_many'
+                for target in targets:
+                    if mustDelete:
+                        # Delete
+                        if target.mayDelete(): target.delete()
+                        else: failed += 1
+                    else:
+                        # Link or unlink
+                        exec 'self.%sObject(obj, target)' % action.split('_')[0]
+                if failed:
+                    msg = obj.translate('action_partial', mapping={'nb':failed})
         urlBack = obj.getUrl(rq['HTTP_REFERER'])
-        if not failed:
-            msg = obj.translate('action_done')
-        else:
-            msg = obj.translate('action_partial', mapping={'nb':failed})
+        if not msg: msg = obj.translate('action_done')
         obj.say(msg)
         tool.goto(urlBack)
 
diff --git a/gen/mixins/__init__.py b/gen/mixins/__init__.py
index 41d9c6f..0b321ec 100644
--- a/gen/mixins/__init__.py
+++ b/gen/mixins/__init__.py
@@ -1175,7 +1175,7 @@ class BaseMixin:
         if not msg:
             # Use the default i18n messages
             suffix = 'ko'
-            if successfull: suffix = 'ok'
+            if successfull: suffix = 'done'
             msg = self.translate('action_%s' % suffix)
         if (resultType == 'computation') or not successfull:
             self.say(msg)
diff --git a/gen/tr/Appy.pot b/gen/tr/Appy.pot
index ac3b779..76f6d27 100644
--- a/gen/tr/Appy.pot
+++ b/gen/tr/Appy.pot
@@ -43,6 +43,10 @@ msgstr ""
 msgid "appy_title"
 msgstr ""
 
+#. Default: "Ok"
+msgid "appy_ok"
+msgstr ""
+
 #. Default: "Data change"
 msgid "data_change"
 msgstr ""
@@ -91,14 +95,6 @@ msgstr ""
 msgid "selected_objects"
 msgstr ""
 
-#. Default: "The action has been successfully executed."
-msgid "action_ok"
-msgstr ""
-
-#. Default: "A problem occurred while executing the action."
-msgid "action_ko"
-msgstr ""
-
 #. Default: "Move up"
 msgid "move_up"
 msgstr ""
@@ -227,10 +223,18 @@ msgstr ""
 msgid "action_done"
 msgstr ""
 
+#. Default: "A problem occurred while executing the action."
+msgid "action_ko"
+msgstr ""
+
 #. Default: "Action could not be performed on ${nb} element(s)."
 msgid "action_partial"
 msgstr ""
 
+#. Default: "Action had no effect."
+msgid "action_null"
+msgstr ""
+
 #. Default: "Go to top"
 msgid "goto_first"
 msgstr ""
diff --git a/gen/tr/ar.po b/gen/tr/ar.po
index abb917e..9825119 100644
--- a/gen/tr/ar.po
+++ b/gen/tr/ar.po
@@ -43,6 +43,10 @@ msgstr ""
 msgid "appy_title"
 msgstr ""
 
+#. Default: "Ok"
+msgid "appy_ok"
+msgstr ""
+
 #. Default: "Data change"
 msgid "data_change"
 msgstr ""
@@ -91,14 +95,6 @@ msgstr ""
 msgid "selected_objects"
 msgstr ""
 
-#. Default: "The action has been successfully executed."
-msgid "action_ok"
-msgstr ""
-
-#. Default: "A problem occurred while executing the action."
-msgid "action_ko"
-msgstr ""
-
 #. Default: "Move up"
 msgid "move_up"
 msgstr ""
@@ -227,10 +223,18 @@ msgstr ""
 msgid "action_done"
 msgstr ""
 
+#. Default: "A problem occurred while executing the action."
+msgid "action_ko"
+msgstr ""
+
 #. Default: "Action could not be performed on ${nb} element(s)."
 msgid "action_partial"
 msgstr ""
 
+#. Default: "Action had no effect."
+msgid "action_null"
+msgstr ""
+
 #. Default: "Go to top"
 msgid "goto_first"
 msgstr ""
diff --git a/gen/tr/de.po b/gen/tr/de.po
index b2fdc26..6ac8812 100644
--- a/gen/tr/de.po
+++ b/gen/tr/de.po
@@ -43,6 +43,10 @@ msgstr ""
 msgid "appy_title"
 msgstr "Titel"
 
+#. Default: "Ok"
+msgid "appy_ok"
+msgstr ""
+
 #. Default: "Data change"
 msgid "data_change"
 msgstr "Änderung der Angaben"
@@ -91,14 +95,6 @@ msgstr ""
 msgid "selected_objects"
 msgstr ""
 
-#. Default: "The action has been successfully executed."
-msgid "action_ok"
-msgstr "Der Auftrag wird ausgeführt."
-
-#. Default: "A problem occurred while executing the action."
-msgid "action_ko"
-msgstr "Ein Problem ist aufgetreten."
-
 #. Default: "Move up"
 msgid "move_up"
 msgstr "Nach oben verschieben"
@@ -225,12 +221,20 @@ msgstr ""
 
 #. Default: "The action has been performed."
 msgid "action_done"
-msgstr ""
+msgstr "Der Auftrag wird ausgeführt."
+
+#. Default: "A problem occurred while executing the action."
+msgid "action_ko"
+msgstr "Ein Problem ist aufgetreten."
 
 #. Default: "Action could not be performed on ${nb} element(s)."
 msgid "action_partial"
 msgstr ""
 
+#. Default: "Action had no effect."
+msgid "action_null"
+msgstr ""
+
 #. Default: "Go to top"
 msgid "goto_first"
 msgstr "Zurück zum Anfang"
diff --git a/gen/tr/en.po b/gen/tr/en.po
index aaa9d67..68ae252 100644
--- a/gen/tr/en.po
+++ b/gen/tr/en.po
@@ -44,6 +44,10 @@ msgstr "Owner"
 msgid "appy_title"
 msgstr "Title"
 
+#. Default: "Ok"
+msgid "appy_ok"
+msgstr "Ok"
+
 #. Default: "Data change"
 msgid "data_change"
 msgstr "Data change"
@@ -92,14 +96,6 @@ msgstr "Selectable elements"
 msgid "selected_objects"
 msgstr "Inserted elements"
 
-#. Default: "The action has been successfully executed."
-msgid "action_ok"
-msgstr "The action has been successfully executed."
-
-#. Default: "A problem occurred while executing the action."
-msgid "action_ko"
-msgstr "A problem occurred while executing the action."
-
 #. Default: "Move up"
 msgid "move_up"
 msgstr "Move up"
@@ -202,7 +198,7 @@ msgstr "Unlink"
 
 #. Default: "Remove selection"
 msgid "object_unlink_many"
-msgstr ""
+msgstr "Remove selection"
 
 #. Default: "Insert"
 msgid "object_link"
@@ -222,16 +218,24 @@ msgstr "Unlock"
 
 #. Default: "Are you sure?"
 msgid "action_confirm"
-msgstr ""
+msgstr "Are you sure?"
 
 #. Default: "The action has been performed."
 msgid "action_done"
-msgstr ""
+msgstr "The action has been performed."
+
+#. Default: "A problem occurred while executing the action."
+msgid "action_ko"
+msgstr "A problem occurred while executing the action."
 
 #. Default: "Action could not be performed on ${nb} element(s)."
 msgid "action_partial"
 msgstr "Action could not be performed on ${nb} element(s)."
 
+#. Default: "Action had no effect."
+msgid "action_null"
+msgstr "Action had no effect."
+
 #. Default: "Go to top"
 msgid "goto_first"
 msgstr "Go to top"
diff --git a/gen/tr/es.po b/gen/tr/es.po
index 6ccd260..2589b38 100644
--- a/gen/tr/es.po
+++ b/gen/tr/es.po
@@ -43,6 +43,10 @@ msgstr ""
 msgid "appy_title"
 msgstr "Título"
 
+#. Default: "Ok"
+msgid "appy_ok"
+msgstr ""
+
 #. Default: "Data change"
 msgid "data_change"
 msgstr "Cambio de datos"
@@ -91,14 +95,6 @@ msgstr ""
 msgid "selected_objects"
 msgstr ""
 
-#. Default: "The action has been successfully executed."
-msgid "action_ok"
-msgstr "La acción ha sido efectuada."
-
-#. Default: "A problem occurred while executing the action."
-msgid "action_ko"
-msgstr "Ha surgido un problema."
-
 #. Default: "Move up"
 msgid "move_up"
 msgstr "Mueva hacia arriba"
@@ -225,12 +221,20 @@ msgstr "¿Está seguro?"
 
 #. Default: "The action has been performed."
 msgid "action_done"
-msgstr ""
+msgstr "La acción ha sido efectuada."
+
+#. Default: "A problem occurred while executing the action."
+msgid "action_ko"
+msgstr "Ha surgido un problema."
 
 #. Default: "Action could not be performed on ${nb} element(s)."
 msgid "action_partial"
 msgstr ""
 
+#. Default: "Action had no effect."
+msgid "action_null"
+msgstr ""
+
 #. Default: "Go to top"
 msgid "goto_first"
 msgstr "Ir al inicio"
diff --git a/gen/tr/fr.po b/gen/tr/fr.po
index 2f32231..02be750 100644
--- a/gen/tr/fr.po
+++ b/gen/tr/fr.po
@@ -44,6 +44,10 @@ msgstr "Propriétaire"
 msgid "appy_title"
 msgstr "Titre"
 
+#. Default: "Ok"
+msgid "appy_ok"
+msgstr "Ok"
+
 #. Default: "Data change"
 msgid "data_change"
 msgstr "Changement de données"
@@ -92,14 +96,6 @@ msgstr "Éléments sélectionnables"
 msgid "selected_objects"
 msgstr "Éléments insérés"
 
-#. Default: "The action has been successfully executed."
-msgid "action_ok"
-msgstr "L'action a été effectuée."
-
-#. Default: "A problem occurred while executing the action."
-msgid "action_ko"
-msgstr "Un problème est survenu."
-
 #. Default: "Move up"
 msgid "move_up"
 msgstr "Déplacer vers le haut"
@@ -228,10 +224,18 @@ msgstr "Êtes-vous sûr?"
 msgid "action_done"
 msgstr "L'action a été réalisée."
 
+#. Default: "A problem occurred while executing the action."
+msgid "action_ko"
+msgstr "Un problème est survenu."
+
 #. Default: "Action could not be performed on ${nb} element(s)."
 msgid "action_partial"
 msgstr "L'action n'a pu être réalisée pour ${nb} élément(s)."
 
+#. Default: "Action had no effect."
+msgid "action_null"
+msgstr "L'action n'a eu aucun effet."
+
 #. Default: "Go to top"
 msgid "goto_first"
 msgstr "Aller au début"
diff --git a/gen/tr/it.po b/gen/tr/it.po
index 7b145ef..9af0a27 100644
--- a/gen/tr/it.po
+++ b/gen/tr/it.po
@@ -43,6 +43,10 @@ msgstr ""
 msgid "appy_title"
 msgstr "Qualifica"
 
+#. Default: "Ok"
+msgid "appy_ok"
+msgstr ""
+
 #. Default: "Data change"
 msgid "data_change"
 msgstr "Revisione dati"
@@ -91,14 +95,6 @@ msgstr ""
 msgid "selected_objects"
 msgstr ""
 
-#. Default: "The action has been successfully executed."
-msgid "action_ok"
-msgstr "L'operazione è stata eseguita con successo"
-
-#. Default: "A problem occurred while executing the action."
-msgid "action_ko"
-msgstr "Si è manifestato un problema"
-
 #. Default: "Move up"
 msgid "move_up"
 msgstr "Su"
@@ -225,12 +221,20 @@ msgstr "È sicuro?"
 
 #. Default: "The action has been performed."
 msgid "action_done"
-msgstr ""
+msgstr "L'operazione è stata eseguita con successo"
+
+#. Default: "A problem occurred while executing the action."
+msgid "action_ko"
+msgstr "Si è manifestato un problema"
 
 #. Default: "Action could not be performed on ${nb} element(s)."
 msgid "action_partial"
 msgstr ""
 
+#. Default: "Action had no effect."
+msgid "action_null"
+msgstr ""
+
 #. Default: "Go to top"
 msgid "goto_first"
 msgstr "Andare all'inizio"
diff --git a/gen/tr/nl.po b/gen/tr/nl.po
index a0de083..5096327 100644
--- a/gen/tr/nl.po
+++ b/gen/tr/nl.po
@@ -43,6 +43,10 @@ msgstr "Eigenaar"
 msgid "appy_title"
 msgstr "Titel"
 
+#. Default: "Ok"
+msgid "appy_ok"
+msgstr ""
+
 #. Default: "Data change"
 msgid "data_change"
 msgstr "Wijziging van de gegevens"
@@ -91,14 +95,6 @@ msgstr ""
 msgid "selected_objects"
 msgstr ""
 
-#. Default: "The action has been successfully executed."
-msgid "action_ok"
-msgstr "De opdracht werd uitgevoerd."
-
-#. Default: "A problem occurred while executing the action."
-msgid "action_ko"
-msgstr "Er heeft zich een probleem voorgedaan."
-
 #. Default: "Move up"
 msgid "move_up"
 msgstr "Verplaats naar boven"
@@ -225,12 +221,20 @@ msgstr ""
 
 #. Default: "The action has been performed."
 msgid "action_done"
-msgstr ""
+msgstr "De opdracht werd uitgevoerd."
+
+#. Default: "A problem occurred while executing the action."
+msgid "action_ko"
+msgstr "Er heeft zich een probleem voorgedaan."
 
 #. Default: "Action could not be performed on ${nb} element(s)."
 msgid "action_partial"
 msgstr ""
 
+#. Default: "Action had no effect."
+msgid "action_null"
+msgstr ""
+
 #. Default: "Go to top"
 msgid "goto_first"
 msgstr "Ga naar het begin"
diff --git a/gen/ui/appy.js b/gen/ui/appy.js
index 24a655c..7bb0d20 100644
--- a/gen/ui/appy.js
+++ b/gen/ui/appy.js
@@ -549,6 +549,11 @@ function onLinkMany(action, id) {
   for (var uid in statuses) uids += uid + ',';
   // Get the array semantics
   var semantics = node['_appy_' + elems[2] + '_sem'];
+  // Show an error messagge if non element is selected.
+  if ((semantics == 'checked') && (Object.keys(statuses).length == 0)) {
+    openPopup('alertPopup', no_elem_selected);
+    return;
+  }
   // Fill the form and ask for a confirmation
   f = document.getElementById('linkForm');
   f.linkAction.value = action + '_many';
@@ -666,7 +671,8 @@ function protectAppyForm() {
 function openPopup(popupId, msg) {
   // Put the message into the popup
   if (msg) {
-    var confirmElem = document.getElementById('appyConfirmText');
+    var msgHook = (popupId == 'alertPopup')? 'appyAlertText': 'appyConfirmText';
+    var confirmElem = document.getElementById(msgHook);
     confirmElem.innerHTML = msg;
   }
   // Open the popup
diff --git a/gen/wrappers/__init__.py b/gen/wrappers/__init__.py
index 7579d49..a507d79 100644
--- a/gen/wrappers/__init__.py
+++ b/gen/wrappers/__init__.py
@@ -156,6 +156,16 @@ class AbstractWrapper(object):
        </form>
       </div>
 
+      <!-- Popup for displaying an error message (~JS alert()) -->
+      <div id="alertPopup" class="popup">
+       <img src=":url('warningBig')" align=":dleft" style="margin-right: 10px"/>
+       <p id="appyAlertText" style="margin-bottom: 15px"></p>
+       <div align="center">
+        <input type="button" onclick="closePopup('alertPopup')"
+               value=":_('appy_ok')"/>
+       </div>
+      </div>
+
       <table class="main" align="center" cellpadding="0">
        <tr class="top">
         <!-- Top banner -->