[tem]

Hi!
you've got to work in a different way to realize what you want to do:
you can use buttons but you have to handle the clips you want to appear trough actionscript or in the timeline:
for example when you rollover on the first button the timelines moves to another frame where there are two buttons...
or when you rollover the button you can set visible the subitems that where set to visible=false..

it depends if you want to work with the timeline or trough code..