Hittest on a duplicated movie impossible? (flashmx2k4)

When you duplicate a movieclip or generate one through AS hittest will allways return true. I tried to make a selection script, by putting the code below into the frame. It makes a rectangle to select charclip movieclips (duplicated and numbered, therefor the for loop) to select them, like when you select icons on a desktop. Unfortunately, it will select all charclips wether theyre inside the rectangle or not. I tried to confirm this behaviour by making a simple hittest script like the one discribed on the kirupa actionscript tutorial, with a moviecript and a duplicated one. The moviescript was detected when it actually hit it, the duplicated one was detected all the time. How do I circumvent this? Should I ducplicate in an existing movieclip or something?

_root.createEmptyMovieClip(“sfield”,10000000);
_root.onMouseDown = function(){
x=_xmouse;
y=_ymouse;
this.onMouseMove = function(){
sfield.clear();
sfield.lineStyle(1,0,100);
sfield.moveTo(x,y);
sfield.lineTo(_xmouse,y);
sfield.lineTo(_xmouse,_ymouse);
sfield.lineTo(x,_ymouse);
sfield.lineTo(x,y);
updateAfterEvent();
}
}
_root.onMouseUp = function(){
for(a=1;a>=_root.o;a–){
if(_root.sfield, hitTest("_root.charclip"+a)){
_root[“charclip”+a].select=1;
_root[“charclip”+a].gotoAndStop(2);
}
}
sfield.clear();
this.onMouseMove = null;
}