Dashboard gauge wont light up

I have a 1993 Toyota Corolla and after installing a new head unit because the factory didn't work, my front dashboard gauge lights wont light up after i turn on the head lights. I have checked all the fuses under the hood and in the under the drivers panel they are all ok. Now is there some wiring i should look into or any other tip that some one can give to me to check out will be greatly appreciated.