I have followed this to the letter but still can't get a wireless connection.
Having had no joy doing the setup via wi-fi ("Unexpected Error" message every time), I have connected the AEX via ethernet and seem to be able to complete the process, however on completion Airport Utility tells me it cannot find the wi-fi network I have specified. At no stage during the setup does it ask me for the network key, only for a password for base station. I have gone on to edit the wi-fi password in Airport Utility whilst connected via ethernet, however it still says "This AirPort base station is set up to join a specific wireless network that can't be found."
The status also says it has no Internet Connection or DNS Servers.
I have triple checked both my wireless network SSID and password (I'm connected via it as I write).
Using AirPort Utility 6.1, and updated the Airplay Express firmware to 7.6.1.
Suggestions?
iMac (20-inch Early 2008), Mac OS X (10.7.4), Cisco E2000 router running dd-wrt.