tail light goes out when Brake pedal is depressed

[Tridaddy]

I have a 97 Integra, the left brake light is having issues. When I have either the marker lights or headlights on the rear tail lights work fine. When the the lights are off and I depress the brake light the rear left tail light comes on, not the brake light. The right brake light operates normal. With the marker/headlights on and depressing the brake pedal the left tail light goes out and the brake light never comes on. Again the right tail light works fine.

I have swapped the bulbs back and forth so I know it is not a bulb issue. The ground seems to be fine based on doing a reading with a multimeter.

Any help is appreciated.