ActionScript 2.0 :: Mouseout Not Recognized When Cursor Go Off Button

I have created a button for fade-in and fade-out, when cursor goes over that button, one of its element fades-in and when cursor goes out it fades-out. But if I quickly moves the cursor over and out that button, most of the time it gets stuck on fade-in ( it doesn't fade-out as cursor quickly goes out of that movie-clip area).

I am using following AS :
on(mouseOver){
// fade-in element
} on(mouseOut){
// fade-out element
}