Complex button rollover/rollout effects trouble

i’ve worked w/ the source file from the tutorials, but the problem i’m having is that ideally, i’d like the current button which is being rolled over to always be on top. so when i have 2 buttons right next to eachother, when either of them zoom, they’ll be on top of the other one. as of right now, that doesn’t happen since either one is in front or behind the next.

any suggestions?