Guess what? When i try to restore the save that you gave to me, Gba Backup does it, but when I start playing the actual game, the cartridge still loads the old save, the one i backupped from the cartridge.
I honestly think that the problem is not in the saves, but, somehow, the problem is in the rom itself, the one from the cartridge. At least, i guess, since the size of this ruby rom is 32 mb, while the rom i took from Pokemon Sapphire is only 16 MB. But again, i don't know crap about how VBA technically works, so it's just a wild guess.