Hi barendth13!
Did you bought Dead Space 2 second hand for your console? In this case, you need to purchase an Online Pass via the PSN or Xbox marketplace to have access to the multiplayer part of the game. If you purchased the game new, you need to ask your retailer for an replacement first.
Cheers
Basti
it brand new it was registered with my email and then sudenly when i wanted to go online it sais it registered with other account i used it before then it was fine but the next time i want to go online it doesnt ant to beacouse it says it registered with another account what can i do
