vpn connection locked on off

[merkedanke vmail me]

hi,
I installed a network-manager plugin on Debian 7 to access at my vpn and 
succeeded it ; like i did yet before on ubuntu 14.04 ; following the 
advices of my vpn provider.
With ubuntu it works like a charm but not on debian where VPN 
Connections (on the task bar) is locked " off ".
i understand that these are not in the same version of software and 
gnome depending of the operating system but it does not explain the 
reason why it is blocked with debian ...


Is it a bug from network-manager (gnome) or from debian (openvpn) ?

Thx by advance for yours answers.