Xbox 360 Wireless A/b/g Adapter Help?

I just recently bought a Xbox 360 Wireless A/B/G Adapter and am having some trouble with it. The problem is that it can’t find my wireless network (which I don’t know why; my Xbox is in the basement, and the router is right above it on the first floor). Because of this, I need to manually type the network name, security type and password. After that, I go back to “Basic Settings”, and it shows that all the IP address settings and all DNS settings are not filled out, even though they’re set to Automatic. Can anyone explain what I’m doing wrong or how I should fill out the settings manually? I’m using a Linksys router, btw.