How to Control external swf?

hi, all

as3 is new for me, but i would like to write a script using loader to load an external swf, and control the external swf. But I find I can’t control the swf, because there are no fixed instance name.

here is my script.

function startLoad() {
var mLoader:Loader = new Loader();

var mRequest:URLRequest=new URLRequest(“child.swf”);
mLoader.contentLoaderInfo.addEventListener(Event.COMPLETE, onCompleteHandler);
mLoader.contentLoaderInfo.addEventListener(ProgressEvent.PROGRESS, onProgressHandler);
mLoader.load(mRequest);
}

function onCompleteHandler(loadEvent:Event) {
this.holder_mc.addChild(loadEvent.currentTarget.content);
// control the external swf
this.holder_mc.gotoAndPlay(12);
}

function onProgressHandler(mProgress:ProgressEvent) {
var percent:Number=mProgress.bytesLoaded/mProgress.bytesTotal;
trace(percent);
}

I could see the external swf, but i can’t control it at all.

i pressed “list object” when it published, i see movieclips inside the external swf listed out and named as “level0.holder_mc.instanceXX(a number).xxxx_mc”. But the number after the instance change everytime. I don’t know how can I control the external swf? is there anyone can help me. thanks a lot.