TypeError: Could not convert list item to float

[new_horizon]

Apologies, here is the full traceback...

Traceback (most recent call last):
File "C:\Program Files\WorldViz\Vizard30/python\viz.py", line 9091, in __update
self.nextAction(pool)
File "C:\Program Files\WorldViz\Vizard30/python\viz.py", line 9144, in nextAction
callAction.begin(newAction._obj_)
File "C:\Program Files\WorldViz\Vizard30/python\vizact.py", line 469, in begin
self.begin_node(object)
File "C:\Program Files\WorldViz\Vizard30/python\vizact.py", line 507, in begin_node
distance = vizmat.Distance(self.beginLoc,self.endLoc)
TypeError: Could not convert list item to float

Thanks