Problem with mask

hey, ive been working on a project for class and i wanted to make a button that when you roll over the text scrolls down and roll off it goes back up. what i did is create a white box above the botton that hides the text as it scrolls in and out. i did that but now im having a problem masking it so it looks right on my background. whenever i mask it, the timeline plays right but when i test the movie nothing happens. i have tried masking any help is appreciated because ive looked all over the place and cant find anything yet. the order of the layers are button->mask->text layer 1 -> text layer2…with both text 1 and 2 being masked by the “mask”. thanks