Hacking Mario Kart DS problem

[Irissama]

Hey folks, I'm brand out of ideas... I've been TRYING to get online with my MKDS on M3 DS Real and it just won't connect! It says it does not detect my router. (51300 error or something)

-I can go online with other games (Castlevania Ecclesia and Picross connects)
-I tried different roms.
-I tried different sakuras.

Anyone got the same problem? Anyone knows the problem??