I have an AirPort Express with a closed network. Sometimes the network does not appear in the status icon and I have to choose Other and enter the SSID and password manually. I was surprised that I couldn't go to System Properties > Network and double-click the network from that list, since the network is known to my computer.

Am I correct that there's not another way to join a closed network that I've connected to before but for some reason it doesn't appear in the status icon?

I'm a novice to Mac networking so hopefully I'm not missing something too obvious.