Parking Lights/Perimeter Lights

Whatever name you call them by, they don't work on my 1996 Buick Riviera. The Headlights, turn signals, and brake lights work, but none of the perimeter/parking lights work, and the dash lights are also out.

I have checked the related fuses front and rear (according to the owner's manual), and no fuses are broken.

If anyone has some suggestions on what this is, or how best to track it down, I would really appreciate the information.