Issue transfering Fire Emblem Sacred Stones from PC to original cartridge

Hi everyone! I don't know if this post goes here because I'm newbie, but here I go with my problem.
I have my own save of Fire Emblem Sacred Stones in my computer. Some days ago I buyed the original cartridge (I'm from Spain, so it's EUR5) and now I want to send my save to the cartridge.
I play the game on Visual Boy Advance-M. Of course, the ROM is EUR5 too. The save file is 64kb, whose last 32 kb are just zeroes. I can convert the savefile to 32kb with Shunyweb Savegames converter or just trimming it with WinHex, and it works fine when I try it again on the emulator.
Then, I put the save in whichever form (32 or 64kb, it really doen't matter) in my DS flashcart's SD. I use GBA Backup Tool (v 0.10 or v0.21) to thansfer the save to my cartridge. GBA BT seems to work fine (indeed, it works fine with other cartridges) and writes de savedata in the cartridge.
But, then, I start the game and... My files are gone. It writes the extra data and I get all my songs and support conversations, but the rest is missing.
If I create new files and I transfer them to the PC, they work just fine. If I backup that files with GBA BT, overwrite them in the game, and restore with GBA BT, it works fine. But, if I backup the save, play it on my computer and then I send it back to the cartridge, the files disappear again.
What the hell it's happening? It's the emulator? It's the cartridge? Please, help!

 

I'll upload 5 files (you just have to change the extension from txt to sav).
1. Sav created on the cartridge.
2. Friend of mine's save from his own cartridge.
3. Same as 2 but after being copied to my cartridge. Files are gone.
4. My own save in PC.
5. Same as 4 but after being copied to my cartridge. Files are gone.
If you compare with some HEX program 2 and 3 / 4 and 5, you can see that just some random bits change.