Hellow yveronese,
You have to change the button instances. They are now button instances that have a up over down status. You cannot control these by actionscript. I have put a little demo on rapidshare that has a dynamic button menu where the clicked button stays highlited and gets resetted when another button is pressed. I hope you can implement this in your projectfile.
http://rapidshare.com/files/191569753/buttons.fla.htmlgreetz,
walter