flash actionscript: I have a button that moves on the screen from left to right . This is a simple
motion tween.

I have this button initially invisible, hence the button is alpha 0%.

I want to make this button visible anywhere along the motion tween.

So when my event takes place that I want the button to become visible, I set
Button._alpha =100.

Once I do this, the button no longer moves in the motion tween.

Am I trying to change the _alpha properties incorrectly for a button contained
in a tween? Do I need to do it another way?

Any ideas gratefully received.