A basic understanding problem path and function

1

i wrote a function that attaches a MC that is dragged and tests a hittest for a new location. and it almost works the way i want.but can any bodey explain to me why
only _root.mouseDown works and targetClipbtn.mouseDown doesnt?
and why when i add the second part of the code _root.onMouseUp nothing works?
(i put all the code…)


function rope() {
 //creating  and attaching an mc(ropeBtn) to it in order to drag it 
 this.createEmptyMovieClip("targetClipbtn", 1);
 this.targetClipbtn._x = 143.45;
 this.targetClipbtn._y = 83.5;
 this.targetClipbtn.attachMovie("ropeBtn", "ropeBtn11", 1);
 //finding th x and y of the mouse and compareing it to my MC with(hitTest)and start dragging
 _root.onMouseDown = function() {
  mxx = _xmouse;
  my = _ymouse;
  if (this.targetClipbtn.hitTest(mxx, my, true)) {
   this.targetClipbtn.startDrag();
   //comparing with the new location
   onMouseMove = function () {
    if (this.targetClipbtn.hitTest(243, 127.25, true)) {
     this.targetClipbtn.removeMovieClip();
    }
   };
  }
 };
}
rope();
 



_root.onMouseUp = function():Void  {
 delete (_root.onMouseDown);
 delete (_root.onMouseMove);
 updateAfterEvent();
};