iPhone 3G Scrabble WiFi Multiplayer - Always "Connection Lost"

My wife and I both have Scrabble for our iPhone 3Gs. Our hope, of course, was to be able to play against each other on our WiFi network. We have an Airport Express that works fine with everything else.

Every time we try to play Scrabble on our phones on the WiFi network, the game quits out, claiming "connection lost" between players. I've searched Google, and while people tend not to have favorable about the Scrabble game in general, I cannot find any mention of this problem or how to address it. For the record, the app works fine in single player for both of us.

We also tried to connect on another WiFi network. This leads me to believe that the problem might be with the Scrabble install on one of our phones. I've uninstalled and reinstalled it on my phone, but not on hers. The problem persists, unfortunately.

Does anybody have any suggestions about how to fix the WiFi multiplayer in Scrabble? What might we need to do in order to get it to work for us?

Thanks for the help.