问拖放AS3:拖动包含动态和输入文本的mc时出错

EN

var itemArray:Array = [
                    {iname:"police",ititle:"POLICE OFFICER"},
                    {iname:"insurance_assessor",ititle:"INSURANCE ASSESSOR"},
                    {iname:"estimator",ititle:"ESTIMATOR"}
                    ];
for (var i:int=0; i < itemArray.length; i++) 
{ 
 var itemname:String = itemArray[i].iname;
 var curritem:MovieClip = MovieClip(scrollitems.getChildByName(itemname)); 
 if (curritem != null) 
 { 
   curritem.ititle.text = itemArray[i].ititle;
   curritem.addEventListener(MouseEvent.MOUSE_DOWN, pickUp); 
   curritem.addEventListener(MouseEvent.MOUSE_UP, dropIt); 
   curritem.buttonMode = true; 
 }
}

function pickUp(event:MouseEvent):void
{
  var dragIt:MovieClip = MovieClip(event.target);   //type casting
  var dragPoint:Point = dragIt.parent.localToGlobal(new Point(dragIt.x,dragIt.y));
  dragIt.parent.removeChild(dragIt); // remove item from current parent mc
  stage.addChild(dragIt); //temp add to stage
  dragIt.x = dragPoint.x;
  dragIt.y = dragPoint.y;
  dragIt.startDrag();
}