help with button animation(hitzone)

[danknugs]

hello, im having a problem with my animated buttons, what is supposed to happen is when you rollover the button it moves down and to left a little. here is my action script:


onClipEvent (enterFrame) {
if (this.hitTest(_root._xmouse, _root._ymouse, true)) {
this.nextFrame();
} else {
this.prevFrame();
}
}
on(release){_root.gotoAndPlay(125);

}

everything works fine but the bounding box on the graphic is not exact, its large rectangle, so when you rollover not even on the button it animates. is there a way i can just put a hitzone so when i only rollover a specific spot it will play that animation? Please help