Which version are you on now? Which kind of router are you using?
I'm using a WRT54G and I can get to the Nintendo Zone, but I can't get my Streetpasses.
I dug out my old WRT54G (v2.2) router and reinstalled DDWRT on it. I am able to see Nintendo Zone and connect, but I can't get any passes. I installed InSSIDer and I can see its broadcasting the right MAC address. Could my version of the WRT54G be the problem?