How to play button animation on Down state?

A very quick question, almost not worthy of me asking i spose…

I’ve got a white outline around a button that fades up on mouse over and fade out on mouse down. I’ve done it by creating alpha tween of the outline in 2 separate movie clips and dropping each clip onto the correct frame of the button symbol.

Question is - how do i get the down state movie to play to the end? If i click and hold the fade-out anim plays ok, but if i click quickly (as everybody does) it’ll only play like 1 or 2 frames of the fade out.

Like i said real simple question with answer probably somewhere in my head already, but it’s late and i can’t find it on searches.