Hyundai Repair: brake lights, backup lights, lamp switch

Question
both brake lights don't work, but the rear window brake light does work. I checked lamps and fuses. They check good. What could the problem be? All other lights work.(Tail lights, backup lights, turn signals)

Answer
Since I don't know the year and model of your car, I cannot check the schematic to find out where the problem could be.

In general terms, we know that the brake lamp switch is working and that a fair portion of the wiring is okay simply because the third brake lamp is operational.  If we've determined that the bulbs themselves are not the issue,  then you might check the sockets to be sure the bulbs make good contact in the sockets.