R4 SaveDongle corrupted my Pokemon Pearl

[multiformeingegno]

Hello. I successfully backed up my Pokémon Pearl original cartridge save file to my PC. Then I made some edits with PokeGen, uploaded the file back to my PKM Pearl original cartridge and boom, when I switched on my DS Lite it said "game data has been canceled because was corrupted"... Then I tried to upload to my cartridge the original backup .sav file I had but still the DS Lite told me the data was corrupted. The strange thing is that I can play just fine both the original .sav file and the modified on Desmume!

Have I done something wrong? Firmware on my SaveDongle is 1.3

EDIT: I was forgetting. All .sav files (original and modified) are 512Kb