AS3 and Tweener

Does somebody knows how to cancel an active Tweener command? for example if I roll over a button with this action.

Tweener.addTween(step2, {alpha:1,delay:0.9,time:0.5,transition:“easeInOutSine”});

And suddenly I roll over step3 for example.

Tweener.addTween(step3, {alpha:1,delay:0.9,time:0.5,transition:“easeInOutSine”});

Sometimes it executes the code above showing both steps at the same time. I tried using both ROLL_OVER and MOUSE_OVER on the event listener but if I go over one fast and back it displays both.

Seems like the ROLL_OUT making step2.alpha = 0; is not be working right. Is there a code to cancel that tweener command when I roll over the next one?