Passenger Side Brake Light Stays On .....

[H8Rain]

Back at the tail lights, passenger side, when the car is on the brake light stays illuminated. The drives side and 3rd brake light work fine... off until you press the brake pedal then they light up.

First thing I tried was a new bulb, didn't work. Then I switch the entire socket on the passenger side with the drivers side, but the issue remained on the passenger side.

Any idea what could be the cause of only the passenger side brake light staying on?

Thanks!