Mismatched basic settings are the most common causes of lost wireless connectivity. If the bridge does not associate with a remote bridge, check the following areas.
SSID
To associate, all bridges must use the same SSID. The bridge installation mode SSID is autoinstall and the normal mode default SSID is tsunami. You should verify that the SSID value shown on the Express Setup page is the same for all bridges. You should also verify that the bridges are configured for the proper network role; only one bridge can be configured as the root bridge.
Security Settings
Remote bridges attempting to authenticate to your bridge must support the same security options configured in the bridge, such as WEP, EAP or LEAP, MAC address authentication, Message Integrity Check (MIC), WEP key hashing, and 802.1X protocol versions.
If a non-root bridge is unable to authenticate to your root bridge, verify that the security settings are the same as your bridge settings