Dash Lights on 2000 Buick Regal

My dash lights comes on. But when the head lights come on, the dash lights goes off. What is wrong.

Asked by for the 2000 Buick Regal
Perhaps the dash light dimmer control on your 2000 Buick Regal is all the way off.
The radio light goes out too.
The dimmer controls the radio lights also.