Likely cause: It appears that the security settings entered into the Nintendo DS are not the same as what your wireless router is set to allow, or your router is not able to assign the Nintendo DS an IP address.
How to fix: Make sure the security key and security type are entered into the Nintendo DS exactly as they appear in your router's settings; manually assign an IP address to the Nintendo DS.
How to fix: Make sure the security key and security type are entered into the Nintendo DS exactly as they appear in your router's settings; manually assign an IP address to the Nintendo DS.