Help with Brake lights

[landarts]

I have finally finished up my long build on the Fixrupr project which is a 1972 1/2 Cheyenne truck. I replaced all of the wiring with a American Autowire kit 510089 Classic Update. Can't say enough of how great this kit is. I have all lights working except for brake lights. Tail lights work, blinkers work, just no brake lights. I have a good ground and lights are bright for blinkers and taillights, all wiring, bulbs and fixtures are brand new.

I have checked and the brake light switch under the dash is plugged in, the wire going to the proportional valve is also plugged in. What is the best way to troubleshoot this issue. Thanks!