Symptom: The client can detect the wireless access point, but it cannot connect to the wireless network.

Cause: Security credentials, wireless channel interference, and dead spots can cause this problem. Since wireless is invisible, it can be very difficult to track these problems down without a proper wireless tool.
Resolution: Using a wireless monitoring tool measure the signal strength from the
affected area, and if possible, conduct a site survey in the area to look for rogue or unknown APs. These may be configured for overlapping wireless channels and can affect known-good users. Check for noise in the signal from surrounding access points or from noise inducing devices such as microwaves and cordless phones. Monitor the client as it attempts to connect to the access point and watch for which step fails – association, authentication, or authorization.