Traceback (most recent call last):
  File "/usr/lib/cups/backend/hpfax", line 111, in <module>
    probed_devices = device.probeDevices(None, 'usb,par', filter='fax')
  File "/usr/lib/hplip/base/device.py", line 376, in probeDevices
    raise Error(ERROR_UNABLE_TO_CONTACT_SERVICE)
Error: ('Unable to contact service', 96)