Problem with buttons and movieclips

k, how to solve this problem: 1. Layer there is a button 2. Layer there is a movieclip which overlaps the button.(Idea is tht, the button woulnd’t work, if movieclip overlaps it). Problem: Eaven, if I can’t see the button, if i move with mouse over the moviclip, it activates the button underneath it. Any ideas, whts causing it?