Thrillville Off The Rails - neither version working on M3 DS Simply

Subject says it all - both games tell me it's unable to create a save game file, though there's plenty of space available on the card.I did recently have a problem where I couldn't write anything to the card when it was connected to the pc via the adapter (though the M3 was still fine writing to it). But that's ok now.I've just installed Crash Of The Titans. That works fine. So it seems the card and the M3 are both behaving nicely, and it's just this one game that's broken.Has anyone else got this, or is it just me?

Do you have the latest firmware?If so, you might need to apply an arm7 patch. You can google that.