Q: Showing Green Not showing on Network

Hey, I have an airport express to extended my home network, but when I walk into that room the airport express is showing green but then when I open the airport utilities app to look at the network it shows it as it was apart of the network but now its not (The airport express hasn't moved locations nor has the router) Some times when I restart the extreme it then show it on the network map.
Router: Airport Extreme