I'm on PS3 and couldn't register my online pass. I noticed the ticker bar was still scrolling info, so what I did was quit the game, and go to the Playstation Store. I scrolled over to previous downloads, and redownloaded the pass.
When I went back into the game the online was part was now working, and I was able to download latest roster etc.
Dunno if this will work for everyone, but thought I would put this up anyway to see if it helped. Thanks all