change main movie content from an external movie clip

Hi, Ned, down there was the code, I used 'MovieClip(root)', it debug without problem, but when i click 'buttonMc', it gave me

Error #1010:

    at menu_fla::MainTimeline/clipClick()

.

but if i replace 'MovieClip(root)' with any mc in menu.swf, it work just fine.

on my 'main.swf', i have these

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var newLoader101:Loader = new Loader();

var request:URLRequest = new URLRequest("menu.swf");

newLoader101.load(request);

addChild(newLoader101);

newLoader101.x = 0;

newLoader101.y = 0;

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on my 'menu.swf', i have these

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var newLoader:Loader = new Loader();

var request:URLRequest = new URLRequest("child.swf");

newLoader.load(request);

//newLoader.contentLoaderInfo.addEventListener(Event.COMPLETE,onLoaded);

buttonMc.addEventListener (MouseEvent.CLICK, clipClick);

function clipClick(e:Event):void {

    MovieClip(root).mcMain.addChild(newLoader); <<--

}

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