brake light

My rear right brake light stays on constantly when I have my lights on. When I put my brakes on my left light goes as bright as the right, but then dims like it is supposed to when I let off the brake. The right one stays the same brightness though. It is like I have my emergency brake on, but I don't, and that is the only side that lights up like that. If anyone else has encountered this problem please tell me what I can do or what is wrong. Thx

No chance the bulb is in backwards is there? Single filament bulb or double?

I really hate to admit that it was this simple but yes, the bulb was in backwards and all I had to do is take it out and turn it around. Thx