Airport Express does NOT extend my wireless network until restart

I have an Airport Extreme as my main router and wireless AP. I extend that with an Airport Express.

My problem is if I just plug the express in, it connects fine to the extreme, but will NOT extend my network.

If I restart the express through the airport utility (NOT power cycling it), when it restarts, it then starts extending my wireless network again, and continues to do so until it looses power. When you plug it back into the wall, the same problem happens, and it needs to be restarted through the airport utility to start extending the network again.

I'm wondering if I have a faulty airport express? Or if anyone else has run into this situation?