CD Key Acivation Problem

I have a problem with logging into EA Nation in Battlefield 4. When I have to login into EA Nation, I'm see a error "The CD Key you provided is already registered". I bought a Battlefield 4 - then I downloaded game in the Origin. Singleplayer works fine, but I want to play Online. I reinstalled the game and Origin, but nothing has changed. Please help me! Thanks alot.