ADDED_TO_STAGE - how it works?

programming flash
1

Hello everyone.

I have a clear stage and a code in first frame:

stop();

var clip:MovieClip = new MovieClip();
stage.addChild(clip);

clip.addEventListener(Event.ADDED_TO_STAGE, onAdded);

function onAdded(e:Event):void {
    trace("added!");
}

Event never triggers. Tell me please, why so?