Fuses are good, bulbs are good, tail light illuminates but not the brake lights help

The brake light side of the bulbs is powered by the brake switch and travels thru the turn signal switch.
If the third brake light works, I would guess the problem is in the turn signal switch.

Have you checked for a burned out fuse? Tail lights also (typically) have two filaments. One for parking lights and another for when the brake switch near/on the brake pedal is in the on position. This switch is another possible source of your lack of illumination. Reverse lights should/might be on a different bulb. If you have already verified that the bulbs and fuses are good, try changing/adjusting the physical switch at the brake pedal.

Check that you have a good earth you may need to remove the earth wire from body of vehicle clean erea then replace if not check that the wire to brake bulb is not burnt out you can do this by using another piece of wire going strait from terminal to bulb or with a test light hope this helps

It may sound silly, but check your brake light bulbs to see if they have been installed incorrectly. Brake light bulbs have two filaments, one for tail light, and a brighter one for brake lights. On some cars if the bulb is installed wrong, the brighter filament will stay on for tail lights. The only other thing I can think of is the wrong bulbs have been installed.

brake light switch

sounds like wireing is shorted together. you need to trace down wires and check for bad spots in wireing. also be sure and check plug if you are set up for trailer lights.

You may want to check you fuses. If your fuses are good, check you brake light switch.

Check the fuses to the brake lights , All of the signal and tail lights etc. are usually on one circuit. If not, make sure that the bulbs are good and connecting firmly to the plug.

I would test the brake light switch. maybe its bad

CHECK THE BRAKE LIGHT SWITCH UNDER THE BRAKE PEDAL