AS3 Flash CS3 button behaviour

Hi all,

Very new to this, so my apologies for this very basic question.
I made a button which has a movieclip in the rollover state and a movieclip in the down state. I have added script in the first frame on the main scene to make it go to a URL once clicked but instead I would like it to finish playing the movieclip inside of the down state of the button first before going to the URL.

SCRIPT USED:

design.addEventListener(MouseEvent.CLICK, buttonClickHandler);
function buttonClickHandler(event:MouseEvent):void {
navigateToURL(new URLRequest(“http://WEBSITE”));

}

attachment added. If you hold the mouse down it will play the full movieclip. This is what I would like to play before going to the URL link. Please let me know where I’ve gone wrong. Thankyou