Did you wire the 7 pin male directly to the camper wiring?
If so, have you put a meter to the back of the plug to ensure you’re getting 12VDC when the truck lights are on? If not, you’re either on the wrong pin, or the truck side is the problem.
If you do have power there, you’ll need to chase/meter the camper wiring. Does it go to a fuse block, and is there power on both sides of the block? If there is you may have an open circuit or high impedance somewhere down stream. Bad light circuit ground is a possibility. I suspect they use the frame as ground, but not certain of that.
You might also jump from the camper battery to the light circuit to see if you have lights.
Hope that helps, good luck.