Problem with lto sample

[neroita]

Hi all , I'm trying to generate some lto label using lto.py in /src/reportlab/graphics/barcode.
I've see that there is a test() procedure that run if I call the file directly but when I try to run I get:
Traceback (most recent call last):
File "lto.py", line 196, in
test()
File "lto.py", line 172, in test
BaseLTOLabel("RL", count, "3").drawOn(canvas, xpos, ypos)
File "lto.py", line 44, in init
self.height = max(availheight, self.CODEBARHEIGHT)
TypeError: '>' not supported between instances of 'float' and 'NoneType'

Can't it be called directly ?
Where can I find an lto label example ?
Thank's in advance ,
marco.