[reportlab-users] text fields or checkmarks

[Timothy Smith]

File 
"/usr/local/lib/python2.3/site-packages/reportlab/platypus/tables.py", 
line 304, in _elementWidth
return max(map(lambda a, b=s.fontname, 
c=s.fontsize,d=pdfmetrics.stringWidth: d(a,b,c), v))
AttributeError: 'NoneType' object has no attribute 'fontname'

can anyone sheld some light on the above error and what i should be 
looking for? i know that i do NOT have any None types in my lists which 
make up the table, a print of them is here

[[26, '02/01', <PgNumeric instance - precision: 10 scale: 2 value: 
0.00>, <PgNumeric instance - precision: 10 scale: 2 value: 53673.10>, 
<PgNumeric instance - precision: 10 scale: 2 value: 53673.10>, 0, 0, 0, 
<PgNumeric instance - precision: 10 scale: 2 value: 14417.70>, 3962, 
<PgNumeric instance - precision: 10 scale: 2 value: 0.00>, <PgNumeric 
instance - precision: 10 scale: 2 value: 13.55>, 0, 0, 0, 0], [27, 
'09/01', <PgNumeric instance - precision: 10 scale: 2 value: 0.00>, 
<PgNumeric instance - precision: 10 scale: 2 value: 32838.30>, 
<PgNumeric instance - precision: 10 scale: 2 value: 32838.30>, 0, 0, 0, 
<PgNumeric instance - precision: 10 scale: 2 value: 8041.20>, 2771, 
<PgNumeric instance - precision: 10 scale: 2 value: 0.00>, <PgNumeric 
instance - precision: 10 scale: 2 value: 11.85>, 0, 0, 0, 0]]

so what is it that could possibly be producing this error?