Mario kart ds friend code is incorrect

In mario kart ds whenever i try to add a friend code it says that it is incorrect, even though it isn't. Any suggestions on how to overcome this? Thanks

 

What flashcart are you using?

 

r4i sdhc

 

do you got a prepatched version or something like that?

 

You have to have same Region of the game.
Like if some has the (U) version and you have the (E) version.
You won't be able to add the persons friend code.

 

I think what johnx said is true, I have got the (U) version. That might be the problem, I'll check that. Hopefully it'll work. Thanks everyone. Its not prepatched btw.

 

Yah.
Because I remember trying to add someone who had a different region of the game.
It didn't work.

 

Just tried it, dont work

On the nintendo website it says that the friend code is 10 digits but all the ones that I've seen are 12 digits. Are you meant to miss 2 numbers out, if so which ones?

 

I'm sure all Friend codes are 12 digits.

 

I dont know whats going on then, oh well can still match people worldwide anyway.