Electrical Advice Needed

I am having problems driving at night. Everything works perfectly until I turn on the headlights. Sometimes the dash lights work, sometimes they don't. When the dash lights come on the fuel and temp gauge stop working. When the dash lights go out, the gauges work. I installed cracked back's headlight harness. My headlights are much brighter but all the other problems remained. Tonite I added a ground to one of the nuts on the cluster. I started the car and turned the headlights on. The dash lights came on at first but then went out. The fuel and temp gauges didn't work at all. I noticed my radio was on. When I touched the dial to turn it off I noticed my dash lights flickered then came back on. When I let go the dash lights went off. When I touched the radio dial the dash came back on. I was turning my dash lights on and off just by touching the radio on/off dial. I guess I was grounding the system. Please help!
Any advice will be greatly appreciated. Thanks FABO.