Why can't airport utility see my airport express?
After purchasing a new airport express the airport utility can't find it. The Mac mini was previously connected to another Express at another location with no problems.
Mac mini, Mac OS X (10.6.8)
Have you kept up to date with the Airport Utility releases? You may very well need v5.6.1. It can be downloaded from here if you don't have it, and it is key to managing the new Airport Express models.