Have You just set up your wireless net at home? If it's new, reset it, and prove it without encryption-just get it online-Once that's going on, add your security encryption, and all should be well.
if you can't, make sure all your incoming cables are in the right place-...not just where they fit, but the proper ones ( sounds simple, but check again)-Airport Extreme base stations have multiple sockets, and you may have the ethernet plug in the wrong spot.
This could be it...
after initially setting it up, you may have to log out, & in again-restart, & start from zero-reset the base station, andwalk all the way through airport setup assistant
Is it an existing network you have proven to work with windows machines, or anything else? Are you sure it's working?
Have you been in both Utilities 1.Airport Administration Utility & 2.Airport Setup Utility?
Try this stuff, and get back to me...
Chhers from Drac