I got another problem. In flex I can only reference the flash button by its ID property. Most of the time I can't know its ID. I need cover it to a super class like MovieClip Instead of that. How can I fix this ? <mx:Script> <![CDATA[ private function clickHandler(event:MouseEvent):void { /* not work */ MovieClip(event.target).gotoAndPlay(MovieClip(event.target).currentLabel); /* only this way can run */ query.gotoAndPlay(query.currentLabel); } ]]> </mx:Script> <local:intergratedQueryButton id="query" click="clickHandler(event)" x="305" y="500"/>