stereo head unit install - instrument panel??

[craftylandshark]

I know I saw this exact issue a week or so ago but searching didn't seem to yeild anything. I just installed a new stereo head unit in place of one that was stolen. Now, some of my gauges don't light up (speedo, tach, enviro buttons), but thanks to a loose connection to one of my brake lights, i know that the trouble indicator lights still work. I didn't alter any wiring except for cutting the old into-head harness off and splicing the new harness straight in. I seem to remember the solution having something to do with the ground wire, but I could be wrong. Any ideas?