DFX-Export: ValueError: invalid literal for float(): 0mm

[Mutschas]

Got this error, after want to export the svg in the attachment to dfx. DFX not created correctly. Don't know why.

Traceback (most recent call last):
  File "dxf_outlines.py", line 345, in <module>
    e.affect()
  File "C:\Program Files\Inkscape\share\extensions\inkex.py", line 268, in affect
    self.effect()
  File "dxf_outlines.py", line 331, in effect
    self.process_group(doc)
  File "dxf_outlines.py", line 289, in process_group
    self.process_group(node)
  File "dxf_outlines.py", line 293, in process_group
    self.process_shape(node, self.groupmat[-1])
  File "dxf_outlines.py", line 211, in process_shape
    x = float(node.get('x'))
ValueError: invalid literal for float(): 0mm

Version: Inkscape 0.91 r13725
System: Windows 8.1 and Windows 7