Index: lams_central/src/flash/org/lamsfoundation/lams/authoring/Application.as
===================================================================
diff -u -r3b92e14873d11f9acaddda38b7ee1587e3aed59c -r9d76eec6f52b6b504919c3e99518a7d51d90cfaa
--- lams_central/src/flash/org/lamsfoundation/lams/authoring/Application.as	(.../Application.as)	(revision 3b92e14873d11f9acaddda38b7ee1587e3aed59c)
+++ lams_central/src/flash/org/lamsfoundation/lams/authoring/Application.as	(.../Application.as)	(revision 9d76eec6f52b6b504919c3e99518a7d51d90cfaa)
@@ -618,7 +618,12 @@
 	
 	public function openEditActivtiyContent():Void{
 		trace("testing openEditActivtiyContent");
-		_canvas.view.getController().activityDoubleClick(_canvas.model.selectedItem);
+		var ca = _canvas.model.selectedItem
+		if (CanvasActivity(ca) != null){ 
+			_canvas.view.getController().activityDoubleClick(ca);
+		}else {
+			LFMessage.showMessageAlert(Dictionary.getValue('al_activity_openContent_invalid'));
+		}
 	}
 	
 	public function paste():Void{