onClipEvent (enterFrame) : On multiple MC's

Hey All,

I have a site with 4 buttons , which all need to fade the same movie clip (contentholder) if rolled over with the mouse.

I can get any one button to nicely fade the movie clip in and out, but when I copy the following code to another button, nothing works.

What am I doing wrong?

onClipEvent (enterFrame) {
	if (this.hitTest(_root._xmouse, _root._ymouse, true)) {
		_root.contentholder._alpha += (10-_root.contentholder._alpha)/5;
		} else {
		_root.contentholder._alpha += (100-_root.contentholder._alpha)/15;

Any help at all would be greatly appreciated.

Many thanks,