Tail Light Problem: Please Help

I turn on my lights and my rear tail lights are lit up, but when I apply the brake the one light then shuts off, even though obviously the bulb hasn't blown because the light works up intill I push the brake. It only goes out on the left side though, the other side works fine. Please someone explain how I can fix this, any help would be greatly appreciated.

My Car is an 98 Civic Ex.

Fixed It. Thanks.