Tail lights Turn signals

All of the lights work fine when used separately turn signals brake lights. But if the brake lights are on and you turn the left turn signal on the right brake light goes out center brake light stays on. Works fine when braking and using right turn signal. Only a problem when using the left with the brakes pressed. The car is a 95 Olds cutlass Supreme 2dr. Coupe
:runaround:

Please post year and model, thanks.