Just spent a frustrating couple of hours.
Set up airport extreme base station all good. Connected via ethernet to an old imac G3. Problems started when trying to attach an express to the network to get stronger signal downstairs.
Firstly reset express by pushing tiny button in with pen until it flashed so back to factory defaults. Plugged it in but could not get it to show up in airport utility. I followed through the settings etc as indicated on the help pages, so, clicked on wireless and then on participate in a wds network
From the test it seems to indicate that the next step is to go to the wds tab and select wds main since the basestation is the main station. I then added the airport id of the express using the numbers on the base of it.
Now when I click update the whole thing locks up. The airport utility just sits there spinning saying I can either wait for the base station to restart or close the window, but nothing happens and the base station doesn't restart.
I'm forced to pull the plug on it and then it blinks orange so I have ot reset it and set it up as a stand alone base station.
Obvioulsy I'm missing something here. I'm guessing it's not working because the express won't show up in the utility window.