发生Flash AS3＃2025错误，将movieclip从加载程序传递到舞台

Question

我只是将动画片段从装载机移到舞台上。

但是当我尝试移动或旋转动画片段时，我遇到了错误“＃2025”。

错误＃2025：提供的DisplayObject必须是调用者的子级

我的代码出了什么问题？

[主要家长MC]

function loaderShow(url:String):void{
    var urlRequest:URLRequest = new URLRequest(url);
    loader.contentLoaderInfo.addEventListener(Event.COMPLETE, loader_complete);
    loader.load(urlRequest);
    addChild(loader);
}

function loaderClose():void{
    loader.unload();
    removeChild(loader);
}

function loader_complete(evt:Event):void {
    var target_mc:Loader = evt.currentTarget.loader as Loader;
    target_mc.x = (stage.stageWidth - target_mc.width) / 2;
    target_mc.y = (stage.stageHeight - target_mc.height) / 2;
}

function addTextEmoticon(ty:int, target:DisplayObject):void{
    var mc:MovieClip = target as MovieClip;
    addChild(mc);
    mc.x = 10; // error occured #2025
    mc.y =20;  // error occured #2025
}

[儿童MC - 装载机]

function clickHandler(e:MouseEvent):void{
    var mc:MovieClip = e.currentTarget as MovieClip;
    root_movie.addTextEmoticon(1, mc);
    root_movie.loaderClose();
}