91 Honda Accord - Dash light problem

What's up? I just recently had a problem come up with my 91 Honda Accord EX. The dash lights stay on when the headlights are off but when you turn the headlights on, the dash lights turn off, kind of like an opposite reaction then normal. Any ideas on why this happen or better yet any ideas on a way to fix it? There are no after market dash light kits on it yet, was thinking about adding them though and recently I had a radio installed. I pulled the radio out tonight and saw a loose wire that looked like it was coming down from the AC area, the wire was orange/white or yellow/white (was dark so couldnt really tell) and it wasnt wired up (like it had been ripped), not sure what it goes to or if its always been like that. Any ideas or help would be great.

SQiX

There is a yel/wht wire that goes from the radio to the automatic antenna. When it sees voltage, the antenna goes up. When the voltage is absent, the antenna goes down, or at least it is supposed to. Lighting/dimming comes in on the red/blk. Power comes in on the yel/red, freek memory comes in on the wht/yel and has power all the time even when the key is off. Hope this helps. Did it work properly before the new radio was installed? If so, take it back and make them fix it.