Flash MX - startDrag, stopDrag?

I can’t seem to get the MC drag to stop

onClipEvent (enterFrame) {
if (_root.x==1) {
this._alpha = 100;
startDrag(_root.card_gallery, true);
} else {
this._alpha = 0;
stopDrag();
this.card_gallery;
}
}

-button rollover code
on (rollOver) {
_root.x = 1;
_root.card_gallery.gotoAndStop(1);
Mouse.hide();

}
on (rollOut) {
_root.x = 0;
_root.card_gallery.gotoAndStop(0);
Mouse.show();

}

How do I get the stopDrag to work?