a few points to pay attention to:

1. in the wifi connection settings, can your ds detect your wireless network?

2. if yes, the wifi settings will test your connection to see if it can connect. does it succeed?

3. if no, try editing the wifi profile, and turn off "obtain ip address automatically", and put in the IP, subnet mask, gateway IP manually. try the test again.

4. if that still fails, get into your router settings, and DMZ your ds.

5. and if that still fails, go into your wireless settings on your router, and set the transmit rate to 1/2Mbps.

this is usually set to "auto", and it will automatically adjust to the ds that uses 1/2Mbps only, but i've had experience with some wireless access points freaking out and refusing to let the ds through unless i set it to 1/2Mbps manually.

djinn: exactly. the most common problems i've run into are either something with the DHCP(thus having to manually set up a static IP address) or the transmit rate(though setting it to 1/2mbps makes your lan a lot slower). check those two first, before DMZing your ds. modern routers are rarely THAT strict as to block the ports that the ds uses.