_parent. or _root.?

I have created a dropzone on the main stage where, when a dragged item is placed it deletes, basically a trash can.

All works fine with this code when both the item and the trash can are on the same level.

onClipEvent (mouseDown) {
if (this.hitTest(_root._xmouse, _root._ymouse)) {
this.startDrag();
}
}
onClipEvent (mouseUp) {
if (this.hitTest(_root._xmouse, _root._ymouse)) {
this.stopDrag();

if (_root.dropzone.hitTest(this._x,this._y,true)) {
	unloadMovie(this);
}

}
}

However the item a movieclip, is placed within a palette, another movie clip. I’ve tried variations of _root. and _parent. but can’t get it to function, anyone any ideas?