When this occurs, try entering the zip code again. You may have entered an incorrect number or there was a momentary network interruption. You can also try entering another zip code near your location that may have the same service provider as you do.
This issue also can occur if you are connected to an unsecured wireless network, such as a Guest network. If you are using a wireless connection, make sure you are connected to a secured Wi-Fi® network (indicated by a lock icon) in the Wi-Fi settings list.