Help with wifi/friend codes

I don't know what I'm doing wrong. Every time I try and get a friend code/connect to wifi with the game, it tells me "No compatible access point in range. Please check your connection settings." Yet, I can connect to the ds store and down load games etc there. Just won't work to go on wifi with this game. Sorry if this doesn't make much sense. I hope someone can figure it out, I want to play with others

[edit to add] when I try and search for my access point, my wireless name doesn't come up in the list. I don't understand!! Why does it let me go on the store,but Ic an't play the game online?