inkscape problem

Hi My name is Rick
I am trying to run MI Servo controller extension and when I setup to just draw a square it gives me this error.

Traceback (most recent call last):
  File "servo.py", line 3172, in <module>
    e.affect()
  File "inkex.py", line 283, in affect
    self.effect()
  File "servo.py", line 3156, in effect
    self.orientation( self.layers[min(0,len(self.layers)-1)] )
  File "servo.py", line 3085, in orientation
    doc_height = inkex.unittouu(self.document.getroot().get('height'))
AttributeError: 'module' object has no attribute 'unittouu'

Being very new at this I have tried several times and get the same error every time. I have setup a notebook and a desktop computer thinking that it is a computer problem? Installed the extensions on both systems and get the same error.