no lights on electronic dash

I have no lights on my dash when I turn on the head lights or the running lights-- when neither is turned on the electronic dash lights work-- Cant see it being a fuse and also couldnt see the light switch being defective since outide lights work-- This is an electronic dash works without headlights but doesnt light with headlights-- any one ever seen this before-- or know what can fix it?? oh if it matters it is a 90 beretta gt v-6-3.1 auto