I have the same problem guys.
In my 2DS always have the "read error" message, tried with a variety of mSD of 1gb, 2gb, 4gb, 8gb and 16gb from the brands kingston, toshiba, sandisk... 1 or 2 unbranded...
I have tried with 2 diferent red gateway cards ( that works like a charm in the 3ds XL)
And...