Do commercial WiFi games will work fine when you try to connect?
If you have SSID reporting turned off in your router, it won't connect with homebrew apps, but commercial games will.
Try enabling SSID reporting if homebrew WiFi is important to you.
My normal setup is SSID reporting off, WEP encryption enabled and MAC filtering enabled. Homebrew won't connect that way.
Turning ON SSID reporting let's the DSOrganize web-browser connect, where it didn't before. Most, if not all, homebrew is like that.
SSID is the culprit, all other settings can be left alone. It MUST be enabled for homebrew WiFi.
Hope that helps you.