Saving my platinum erases my disgaea!

I noticed this when it erased my desgaea game with 8 hours of gameplay!!
After this first happened i began to backup my saves on my computer. This is how it happens.Every time that i save my pokemon platinum on my R4 (version 1.18) i turn it off and boot up disgaea, and my save is gone!! the actual file is there but its empty!! So i have to pull up a backup every time!i tried formatting my SD card.i also tried putting both games in different folders but it happens every time!Both roms are (U)
Anybody have some tips?

Recover My Files v3.9http://www.mediafire.com/download.php?c3qjnhhmnm5

Have you tried to change the name of the roms? might work.

Perhaps you have not enough memory so it deletes the file to make space?

yeah, might as well leave the rom scene numbers, and just take the (U) crap off, OR just get a new card, like an AceKard2, and maybe a bigger mSD card

Nah, see i have approximately 512MB left in the card (I always leave this much space as a "just in case")I'll try to rename the ROMS, I always rename them and take off the release number and country.
Could there be some issue with the ROM number (i don't know what it's actually called)I'll try downloading another version of PLATINUM, although my current version is the one hosted on this site.Sorry guys, it was after i bought my R4 that i discovered other cards, like AceKard. It's too late now, I got fired =[

well, with 0$ I still managed to get an AceKard2, SuperCard DSONEi, and a dsi.
So yeah, might be some options out there XD