Save files

[tywald]

Are you 100% the games are of the same region? If you are transferring from US to EU versions of the same game or vice versa then most likely that would be the answer. Usually the difference between US and EU versions is that EU version have more language options while the US version is stuck with English. The only exception I can think of right now is Monster Hunter Freedom Unite.

Another possible reason is your PSP cannot load "encrypted saves". You can disable it in PPSSPP if you change this line in ppsspp.ini

EncryptSave = True
to
EncryptSave = False

Load your game and save again.

But I think it's the former, it usually is at least.