Error loading Security module

[Coilz]

Version: Ubuntu Tweak 0.4.9.1
Distribution: Ubuntu 9.10
Desktop environment: GNOME 2.28.1 (Ubuntu 2009-10-23)
Kernel: Linux 2.6.31-14-generic
Platform: i686
Cpu: Mobile AMD Sempron(tm) Processor 3000+

Traceback (most recent call last):
  File "/usr/share/ubuntu-tweak/mainwindow.py", line 567, in setup_notebook
    page = page()
  File "/usr/share/ubuntu-tweak/lockdown.py", line 63, in __init__
    if self.get_proxy.is_exists(ROOT_THEMES) and self.get_proxy.is_exists(ROOT_ICONS):
  File "/usr/share/ubuntu-tweak/common/policykit/dbusproxy.py", line 40, in __getattr__
    return self.__object.get_dbus_method(name, dbus_interface=self.INTERFACE)
AttributeError: 'NoneType' object has no attribute 'get_dbus_method'