Attaching a movie clip to stage

Ok. i have this foolish problem. I need to attach a movie clip to the center of stage.
i have this code on a button:

on(release){
_root.attachMovie(“error”,“error1”, 10);
}

error is the name of a movie clip in library. this doesnt seem to work and ive tried putting this and _parent in place of _root but that still doesnt seem to work.
after i have attached it there should be no problem centering it, but i cant get rid of this problem. please help!

Thx.