rollOut animation for buttons

It seems like such a simple thing to do, and I know my way around actionscript, but for the love of bob I can’t make buttons have animations when the mouse leaves their areas as well as when it goes on them.
I tried just using the up frame without the over one and putting a movieclip in the ‘up’ frame of the button and then doing something like on (rollOver) {this.the_movieclip.gotoAndPlay(6) } but I can’t get to influence things inside a button.
So, I know how to make a button do an animation when you roll over with the mouse but I need to know how to play one when you roll out.
All help is greatly appreciated.