Running/Tail lights on trailer not working!!

Guys i have 2000 volvo vnl 770 all the lights in my truck works perfectly but in the trailer running and tail lights don’t work, turn signals and stop lights work just fine.

I checked my fuse they’re all good, flasher relay bought it new at the dealer. Bought a new pigtail and i still don’t have power on the brown wire wich is the one for running/tail lights.

Please any help it will be really appreciated!!

 

Thanks i will check there later on today.

 

Found the problem!!! The plugs from under the cab driver side was all mess up cleaned plug back in and all good!!