This happens if you are not connected to the internet when you connect to calibre as a wireless device, for example if your home network normally has no internet connection.
You can fix this problem by doing the following steps 1 time.
- Ensure that your device is connected to the internet. This can be on your home network after connecting to the internet, in a coffee shop, or via a cellular link (tethered or native). If via a native cellular connection (one on the device in question, not tethered), be sure to tell CC that connecting over "3G" is permitted (Settings / Connecting to calibre / Wireless device connection/ IP address and port / Allow connecting using 3g)
- In CC, attempt to connect to calibre as a wireless device. This connection will probably fail because your library isn't visible, but in the meantime CC will verify your license.
- Reset your network to what you normally use.
CC will remember the license until it is uninstalled or you do a "Clear Data". In these cases you will need to do the above steps again.