96 rs camaro radio works only if lights are on?

i got a 96 rs with a aftermarket radio and for some reasone the deck wont work inless the head lights are on and if the running lights are on it works as well but if the headlight switch is off then the deck has no power any idea on wat this is. the deck is wired right so there has to be something more also if the power acc. fuse is in the running lights come on so i hav to leave it out.

Aren't the wires for an aftermarket deck black/ground yellow/battery and red/sensor... so what's the sensor wire going to?

And maybe the yellow wire is going to a source that's not always hot (like the headlights) lol