You should select proper network interface to be monitored by VPN Watcher depending on VPN connection type you use.
Most VPN providers offer PPTP, L2TP and OpenVPN connection types.
Just select your VPN connection from “Connections” drop down list and the program will automatically start the monitoring process. You also may use the “Connect” button to enable/disable your VPN connection instead of using built-in OS interface.
If you use OpenVPN connection – you should select the network interface created during your VPN client installation process. See the corresponding tutorial for details.