Also make sure that you are redeeming it in the correct region. The USA and Canada did not get that game as a Plus premium yet, so that code is only valid in some other region's Playstation Stores. Probably Europe. All Playstation Plus codes are region, or even country, specific. You can just redeem it on any PSN account that you want. It has to be an account that is registered in the same region that the code is from.