Express cant extend wireless network

I have a Airport Exteme which I use as my wireless base-station. For two years I used an Express to extend the network wirelessly. It worked fine but this week it died so I gought a new one.

However I can not wirelessely extend the wireless network using this new Airport Express. It works fine using an ethernet cable but this isnt covnenent. The issue is when I get to the screen that says "Select the Apple wireless device you want to extend. If you are not sure click Identify. If your Apple wireless device is not on the list click Scan Again". The list is empty no matter how many times I hit rescan.

Am I missing something?

Thanks in advance.