Downloadable Content for the PlayStation 3?

So I was looking at the downloadable content for the PS3 and I found the Marvel Ultimate Alliance 2 character add-ons back. So I downloaded the one where you can get Magneto, Psylocke, Cable, and Carnage, but when I started up my game and when I tried to switch those characters to my team, they were not there. Can someone please tell me how to fix this and how to active the downloadable content? Thank you for your time.