[Zope] Using ZGDChart with a python script as data method

[Josh]

Hi, I am attempting to use data gathered by a python script to create a chart 
with zgdchart.
 
I am using zope 2.6.4, zgdchart 0.6.4 on windows 2000.
 
Within a zgdchart object, if I use a dtml method as the data method with code 
such as:
 
<dtml-return "(('syd','melb','bris', 'adel', 'perth'),(5, 7, 6, 4, 6),(5, 10, 
5, 1, 6))">
 
the chart works fine.

When I try to use a python script as the data method, with code such as:
  
return (('syd','melb','bris', 'adel', 'perth'),(5, 7, 6, 4, 6),(5, 10, 5, 1, 
6))
 
the chart fails to be produced. 
 
Can anyone provide any tips?
 
Thanks, Josh