GBA save issues - Pokemon Mystery Dungeon Red

Hello, I've been playing PMDR on my computer using VBA,
for some reason, I can't save with the game. I tried it on 2 different computers and the problem is the same.
can anyone tell me what's wrong?Thanks, Dor.

Maybe your save type needs changing? Go Options then Emulator then Save Type.

Nope, tried it all.
still says save failed.EDIT: this is weird, when I started a new game (saved the previous with F1), it CAN save normally, but when I load the F1, it can't T_T
why?