Nba2K11 Roster Update... How To Convert .ros Files To .iff?

Hello everybody, I downloaded the game but its roster sucks, when I download patches, files ar e"roster.ROS", but my game has "roster.iff" file. if I manually change the extension, the game won't work, does anybody know where can i download a .iff roster file, or how to convert .ros files into .iff? Thank You. #GoLakers