I have been trying to set up a VPN connection by following the instruction on zpn.im
but after restarting the network-manager by typing
sudo /etc/init.d/network-manager restart and going to create a vpn connection, there is no choice of vpn available. The window that appears after pressing the Add button of network connection's dialog box is as follows :
I wonder what a VPN plugin is and how to find and install the appropriate one to fix my problem. Any help or ideas are most appreciated.