FLEX 引用SWF文件中的MC并做控制

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" creationComplete="init()"
layout="absolute" xmlns:mxml="com.eastcomsw.kbq.mxml.*" height="768" width="1024">
    <mx:Script>
        <![CDATA[
            import mx.core.MovieClipAsset;
            import mx.controls.Image;
            import mx.core.UIComponent;

            [Embed(source="assets/kbq/images/attach.swf",symbol="UnAttach")] 
            private static var UnAttach:Class;
            private function init():void
            {
                var ui:UIComponent = new UIComponent();
                var mc:MovieClipAsset = MovieClipAsset(new UnAttach());
                mc.gotoAndStop(19);
                ui.addChild(mc);
                this.addChild(ui);
            }
        ]]>
    </mx:Script>
</mx:Application>