1994 Mercury Sable dash clock problems

I have a problem with the clock in the dash. During
normal daytime driving the clock works fine, light come on and it keeps correct time. When you turn the lights on, daytime or night time, the clock stops keeping time and the light only comes on once in awhile. The time never changes.

I have changed the headlight switch and it has not helped solve the problem, still the same.

Any sugestions or help with this problem???