Crashed after adding a third party source and clicking on edit

Traceback (most recent call last):
  File "/usr/lib/python2.5/site-packages/softwareproperties/kde/SoftwarePropertiesKDE.py", line 582, in on_edit_clicked
    result = dialogue.run()
  File "/usr/lib/python2.5/site-packages/softwareproperties/kde/DialogEdit.py", line 121, in run
    self.sourceslist.list[index] = aptsources.SourceEntry(line,file)
AttributeError: 'module' object has no attribute 'SourceEntry'

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The first crash was directly after adding the beryl-repository to the third-party section, then i started the programm again and tried to edit this software source and it crashed again.