i think maybe it's because you didn't use the RegionFour "hack", because the puzzle and dragon rom is most likely EU (the US one isn't out yet, as far as I know).
RegionFour: http://smealum.net/regionfour/, http://www.sky3ds.com/
My 3DS can't connect to the internet, and gives error 003-2101. I tried to restart the router, 3DS, change the IP, DNS, etc, but it all doesn't work. Any help would be appreciated.