ubuntu tweak daemon could not start

[norton]

Distribution: Ubuntu 12.04 precise
Application: Ubuntu Tweak 0.7.0-0~bzr1819+20120423~precise1
Desktop:ubuntu-2d

Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/ubuntutweak/main.py", line 497, in _load_module
    page = module()
  File "/usr/lib/python2.7/dist-packages/ubuntutweak/tweaks/workarounds.py", line 49, in __init__
    self.set_fix_theme_button_status()
  File "/usr/lib/python2.7/dist-packages/ubuntutweak/tweaks/workarounds.py", line 81, in set_fix_theme_button_status
    self.fix_theme_button.set_active(proxy.is_exists(self.ROOT_THEMES) and proxy.is_exists(self.ROOT_ICONS))
  File "/usr/lib/python2.7/dist-packages/gi/types.py", line 43, in function
    return info.invoke(*args, **kwargs)
TypeError: Argument 1 does not allow None as a value