Adding sound on MOUSE_OVER

1

how can I add sound to a button on rollover?

I have tried this but the sound plays when the page is loaded aswell as when ouse over.

var aboutBtnsnd:Sound = new Sound(new URLRequest("clook.mp3"));
var aboutBtnchannel:SoundChannel = aboutBtnsnd.play();
var aboutBtnpausePosition:int = aboutBtnchannel.position;

Nav.aboutBtn.addEventListener(MouseEvent.MOUSE_OVER, aboutBtnstartSound);
function aboutBtnstartSound(event:MouseEvent):void {
	
	if (aboutBtnchannel == null)
{
aboutBtnchannel = aboutBtnsnd.play(aboutBtnpausePosition);
}
}

Nav.aboutBtn.addEventListener(MouseEvent.MOUSE_OUT, aboutBtnstopSound);
function aboutBtnstopSound(event:MouseEvent):void {
aboutBtnchannel.stop();
aboutBtnchannel = null;
}