Traceback (most recent call last):
  File "/usr/share/system-config-printer/asyncipp.py", line 193, in send_reply
    self._reply_handler (self._conn, result)
  File "/usr/share/system-config-printer/asyncpk1.py", line 125, in _ipp_reply_handler
    self._client_reply_handler (self._conn, *args)
  File "/usr/lib/pymodules/python2.6/cupshelpers/cupshelpers.py", line 564, in _reply_handler
    for uri, data in devices.iteritems():
AttributeError: 'NoneType' object has no attribute 'iteritems'