Comment 6 for bug 590013

This is the error i get:

Traceback (most recent call last):
  File "/usr/bin/ubuntu-tweak", line 110, in <module>
    launcher = TweakLauncher(session_bus, MainWindow())
  File "/usr/lib/python2.6/dist-packages/ubuntutweak/mainwindow.py", line 234, in __init__
    proxy.enable_stable_source()
  File "/usr/lib/python2.6/dist-packages/ubuntutweak/policykit/dbusproxy.py", line 33, in __getattr__
    return self.__proxy.get_dbus_method(name, dbus_interface = self.INTERFACE)
AttributeError: 'NoneType' object has no attribute 'get_dbus_method'