Did you take a look at the list in post #1 ? I see many versions of the R4 So i'm not exactly sure what card you have.
Compatible:
Acekard 2(i) (DSi-Enhanced games, including newer NTR games, don't work.)
Acekard RPG
DSTT
DSTT Advance
Galaxy Eagle
M3 DS Real
M3 DS Simply (uses <2GB microSD...