how to fix error 10057 when trying to connect to airport express

I have 2 Airport Express units. One is connected to my braodband router. I am able to view that in the Airport Utility, and can connect to the internet by connecting to the Airport Express. I now have a 2nd Airport Express unit, to be connected to a stereo so I can play music from my ipad wirelessly. When trying to connect to the 2nd base station using Airport Utility I receive an "error 10057" message. How do I "fix" that error?

The first unit was purchased in UK, the second unit was purchased in USA - does that matter?

Thanks