HondaMang

while swapping in a new set of 99-00 tails I realized that the far left brake light will not light up. The bulb is okay, as the light comes on when I turn on the gauge cluster or headlights, but for some reason it will not turn on when the brake pedal is pushed. Everything other light functions properly. Before getting into too much trouble I wanted to see if anyone could tell me what to do here. Thank You !