Thank you for your help. I was trying to use a 1st Generation Airport Express, and after much research, it looks like it isn't possible with this airport. I went and got the new Airport Express with two ethernet ports and it is working. Set up was very easy. I might be wrong, but it looks like you have to only have a new Airport Express with two ports. That should be stated in the documentation. I found out that even the Presonus mixers can't use the previous generation Airport Express's. Once again, thank you for your replies.
