Flash 8 :: Unable to attachMovie to EmptyMovieClip

Hi guys!
I’m trying to create a scroller menu. The container movieclip will hold several copies of a clip in the library. So I’m trying to create the clip dynamically since it’s width will be varying depending on the number of elements it contains.
But when I try to use the attachMovie method on my newly created empty movieclip, nothing shows up! The test_mc will attach if I just say _root.attachMovie, so I don’t know if it’s a path issue or if emptyMovieClips can’t have other clips attached or what. What am I doing wrong!? =/

var emptyClip:MovieClip = this.createEmptyMovieClip(“empty_mc”, 9);
emptyClip._x = Stage.width / 2;
emptyClip._y = Stage.height / 2;
emptyClip._width = 300;
emptyClip._height = 300;
emptyClip.attachMovie(“test_mc”, “test_mc”, 20);