Nintendo 3DS Download Play Not Working

[Chiraku]

Kay, so here's the sitch.
I just got my 3DS in the mail (happy day) a day or two ago. Shortly thereafter I downloaded Tetris Axis from the eShop (cool game) and after trying it out a few times, me and my bro (Fierce.Diety) tried to play multiplayer via download play, but on his 3DS after the game finishes downloading and the loading screen passes, it always says 'connection error,' and he has to close the software. My game says the same shortly after.
So, what's the deal? Am I missing something I should do with Download and Play? Can two 3DSs not just connect off the bat? Is it an issue with my game?
Tasukete!

 

[Ventus]

It sounds like your 3DS needs to be repaired. My own 3DS and my cousin's 3DS both work perfectly fine. There may be a defect in your brother's 3DS. Have you tried calling Customer Support?

 

[Chiraku]

It sounds like your 3DS needs to be repaired. My own 3DS and my cousin's 3DS both work perfectly fine. There may be a defect in your brother's 3DS. Have you tried calling Customer Support?

Well... no. It never crossed my mind, plus the fact that we're in SE Asia, so if I needed to send it over to get repaired, that would be pretty impractical.
Daggit! I just got this thing!
Do retailers like Gamestop offer repairs, or is the big N the only one?

 

[Chiraku]

Call customer service first to trouble shoot it.

Alright... I'll get to that, I guess.
Thanks for the help.