VPN using pptp is not working - not allowed policies

Hello,

I tried to setup a pptp VPN using NM and I'm unable to connect. After having settings parameters, I activate the VPN in the GUI manager and get in syslog:

Mar 9 11:50:47 localhost gnome-session[2163]: (nm-applet:2407): nm-applet-WARNING **: nma_menu_vpn_item_clicked: no active connection or device

I try to debug and get the policies error:

dh@deex:~$ /usr/lib/NetworkManager/nm-pptp-service --debug
** Message: nm-pptp-service (version 1.1.93) starting...
** Message: Error: failed to create NMPptpPlugin: Connection ":1.161" is not allowed to own the service "org.freedesktop.NetworkManager.pptp" due to security policies in the configuration file

If I execute this command with sudo there is no error but VPN still doesn't start.

The same setup with Ubuntu 14.04.5 LTS is working well

Description: Ubuntu 16.04.2 LTS
Release: 16.04

network-manager-pptp:
  Installé : 1.1.93-1ubuntu1
  Candidat : 1.1.93-1ubuntu1
 Table de version :
 *** 1.1.93-1ubuntu1 500
        500 http://fr.archive.ubuntu.com/ubuntu xenial/main amd64 Packages
        100 /var/lib/dpkg/status

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: network-manager-pptp 1.1.93-1ubuntu1
ProcVersionSignature: Ubuntu 4.4.0-66.87-generic 4.4.44
Uname: Linux 4.4.0-66-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.5
Architecture: amd64
CurrentDesktop: Unity
Date: Thu Mar 9 11:46:04 2017
DistributionChannelDescriptor:
 # This is a distribution channel descriptor
 # For more information see http://wiki.ubuntu.com/DistributionChannelDescriptor
 canonical-oem-somerville-precise-amd64-20130203-1
InstallationDate: Installed on 2013-10-13 (1242 days ago)
InstallationMedia: Ubuntu 12.04 "Precise" - Build amd64 LIVE Binary 20130203-13:50
SourcePackage: network-manager-pptp
UpgradeStatus: Upgraded to xenial on 2016-10-05 (154 days ago)