Ubuntu Tweak 0.70-1 creates error message with log in settings

[Sven.Frings]

Ubuntu Tweak 0.70-1 installed within Xubuntu 12.04

Distribution: Ubuntu 12.04 precise
Application: Ubuntu Tweak 0.7.0-1~precise4
Desktop:xubuntu

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/loginsettings.py", line 82, in __init__
    self._setup_logo_image()
  File "/usr/lib/python2.7/dist-packages/ubuntutweak/tweaks/loginsettings.py", line 95, in _setup_logo_image
    self.logo_image.set_from_file(logo_path)
  File "/usr/lib/python2.7/dist-packages/gi/types.py", line 43, in function
    return info.invoke(*args, **kwargs)
TypeError: Must be string, not NoneType