Custom button extends Sprite

I am writing a class button that extends Sprite. I use graphic fill to draw button and then use addEventListener to add Tween to MouseOver event. Problem is:

  1. If I use MOUSE_OVER event, the tween became sometimes corrupt when Mouse is INSIDE the button.
    2)If I use ROLL_Over event, the tween became sometimes corrupt when Mouse is NEAR the button BUT ok WHEN mouse is far enough.

I remember time when we use INVISIBLE button to capture mouse event probably. Is there any issus with mouse event in AS3 that I as a newbie do not know. Thanks