Leer 100xr 3rd brake light not activating

The 3rd brake light/CHMSL doesn't activate when I press on the brakes, but it will turn on when I turn on my headlights for nighttime driving. The LEDs work and it's receiving power. The camper's dome light works too. What should I do to fix this?

If it matters, it's a 3rd gen TRD Sport. There's a fuse box in the shell and it seems to be doing its job, though I'm not an expert and I didn't install it.

 

How did you connect it into the trucks wiring?

 

My money is on it is wired to the parking circuit (green wire), not the brake (blue wire)

 

Check your wiring manually with the bare harness and label your wires. I got an aliexpress 6 pin harness with all the wrong colors so I just put a 12v battery on my tailgate and labeled what powered what.