Estou criando um jogo no estilo pacman. Estou tentando remover uma instância de um MovieClip usando removeChild (). Quando a instância "Movie" da instância do MovieClip atingir a instância "circle" - o círculo será removido do palco.

Estou recebendo o seguinte erro abaixo:

ArgumentError: Erro # 2025: O DisplayObject fornecido deve ser filho do chamador. em flash.display :: DisplayObjectContainer / removeChild () em Move / eatCircle ()

package {
       import flash.display.Sprite;
       import flash.display.MovieClip;
       import flash.events.Event;
       import flash.events.KeyboardEvent;
       import flash.ui.Keyboard;

       public class Move extends MovieClip {

       var ScoreObjects:Array = new Array(); // creates ScoreObjects array


          private var inertia:int=8; //amount of friction

       var score_field:String;
       //var point:MovieClip;


     // Constructor--------------------------------------------------------------------
          public function Move() {
             init();
          }

     // function init -----------------------------------------------------------------
       function init():void {

             //stage.frameRate=60;
        var score_field:String="";

      ScoreObjects[0] = new Circle();
      ScoreObjects[0].amount = 1; // amount of point
      ScoreObjects[0].name = "circle";


             stage.addEventListener(Event.ENTER_FRAME, frameloop);
             stage.addEventListener(KeyboardEvent.KEY_DOWN,keyDownEvent);
             stage.addEventListener(KeyboardEvent.KEY_UP, keyUpEvent);

        box.addEventListener(Event.ENTER_FRAME, eatCircle);
        wall.addEventListener(Event.ENTER_FRAME, hitWall);

        stage.addChild(ScoreObjects[0]); // add Score Objects to stage ------------------------------
        trace(ScoreObjects[0]);

        ScoreObjects[0].x = 105;
        ScoreObjects[0].y = 233;

          }

     // function eatCircle --------------------------------------------------------------
     function eatCircle(event:Event):void {

      if (box.hitTestObject(ScoreObjects[0])) {
        trace ("I ate the circle");
        removeChild(ScoreObjects[0]);
        //calcScore();
       } else {
        trace ("I didn't eat the circle");
       }
     }



       }// end of class
    }// end of package