I have lost the running lights on my camper. Checked fuses and plug No Joy on 2004 Chevrolet Silverado 2500 HD

I have been over all the fuses in the panel to the right of the steering wheel and the ones under the hood. they are all good. I took the female plug apart no loose wires. I am now officially stumped. The brake lights work. No running lights.

ck all grounds
I'll do it. Thanks. Glen Roberts