[Zope] date formatting

[garry saddington]

I am trying to format a dtml-var date by using fmt=Day
 <dtml-var foo fmt="Day"> returns error: Error Type: TypeError
Error Value: not all arguments converted during string formatting

while <dtml-var ZopeTime fmt="Day"> works fine.

The date is International format and I have Zope set up to parse
international dates.
Does anyone know where I am going wrong?
regards
garry