2001 Cadillac Deville Interior Lights

When the doors are opened, the interior lights do not come on. You can turn the light on with a switch so it is not burned out. Also, I have checked several fuses that might be the circuit for this and they each check out ok. Also, there is the option to turn these off so they don't come on and that is not the problem. We would like to have the light come on but don't know what else to check.
Any advice you can provide is much appreciated.