Also discovered here Quote:
In Flash CS3, when you have instances (Movieclips) on the main timeline (Stage) with instance name on them and “Automatically declare stage instances” is off (File->Publish Setting->Flash->Actionscript 3.0 setting), You will need to declare properties for the document class with the same instance names or else you will get the error messages…
Like:
Cannot create property ANamedClipOnTheTimeline_mc on com.yoursite.DocumentLevelClass
at flash.display::Sprite/constructChildren()
at flash.display::Sprite()
at flash.display::MovieClip()
at com.yoursite.DocumentLevelClass()
In my case this was due to copying a button that didn't belong, hidden behind another clip. To Find it I selected all, Right Clicked, selected distributed to layers, and then deleted the offending layer named that of the clip named in the error.
