BF: BC2 Serial key not working to log into multiplayer

Hello,

Last year i got BFBC2, and played it throughout that year. I haven't played it since december and was looking to re-install it today. The re-installation works and the CD-Key that came with the product works fine to verify the installation. After the installation i update the game, and then go on it. For some reason though, when i try to play online again the serial key doesn't work.

My login details work, i accept the terms and agreements, but then it asks me for my serial key, so i enter the key that came with the game, as that is the only game-key that i can find associated to BFBC2, whether in the manual or in my email. The serial key, no matter how many time i try and enter it, just tells me that the code is already in use.

Can someone please tell me how i am supposed to get around this, because i only play BFBC2 for the multiplayer.

- Alex.