Fail to "erase disk" in usb-creator

[Michal Dziczkowski]

In order to install a ISO on a USB stick with usb-creator, I need to erase it with usb-creator (even if his USB drive is already empty). The problem us that when I'm attempting to use the "Erase disk" function in usb-creator, I get following error after few seconds:

org.freedesktop.DBus.Python.AttributeError: Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/dbus/service.py", line 707, in _message_cb
    retval = candidate_method(self, *args, **keywords)
  File "/usr/share/usb-creator/usb-creator-helper", line 218, in Format
    parent_dev = _get_parent_object(udisks, device)
  File "/usr/share/usb-creator/usb-creator-helper", line 49, in _get_parent_object
    parent = partition.get_cached_property('Table').get_string()
AttributeError: 'NoneType' object has no attribute 'get_cached_property'

My system: Ubuntu 14.04