Attaching an MC inside of ANOTHER movie clilp on stage

[nmuta]

Ok, here's the deal:

I have a movie clip in the library exporting to Actionscript with the name "folder".

I have a button on the main stage that, when you press is , should be using attach movie to create an instance of folder INSIDE of targetMC.

But it's not working.....nothing shows up.

I am doing:

on(release){
    
    _root.targetMC.attachMovie("folder","foldernew", 55);

     _root.targetMC.foldernew._x= _root.targetMC.birthzone._x;
      _root.targetMC.foldernew._y= _root.targetMC.birthzone._y;

}