Hm, sounds to me like you have a US version of Madden connecting with a european account, probably on PS3?
Had the same problem last year, you need to create an US Account if you're on PS3 and log on with that one.
No problem registering my online pass with that. I always play with the US versions because there is no NCAA and therefore no draft class import on european version of Madden, which plain out sucks