Courtesy lights won't come on when doors open

[Mitch]

My courtesy lights won't come on when any of the doors open. 1996 850GLT. The door sensors are OK because the door lights on the door panels turn on, but none of the reading lights in the front or rear turn on. They are all set to the proper switch setting for this. The lights turn on just fine when I depress the switch for manual turn on so the bulbs are OK.

It used to work and stopped one day. Anyone have any ideas what could be wrong?

Thnaks in advance.