And you are sure you picked the right save file, yeah?
POST5_U_23552_usa_9221.bin is the one you need.
If that doesn't work, then there's probably something wrong with the 10.3U save files because I think we've had another person reporting earlier this week that it wasn't working for them on 10.3.0-28U with the Powersaves saves.
(There's two different files in the archive for the two different cardids, but I think if you picked the wrong one the game would just reject the save file as a whole, so that probably isn't the problem.)