[Zope] object attribute access in zpt

Let 'pdate' be a python datetime object. I can do this: 'tal:attribute="value python:now"' However if I try to print out an attribute of 'now', like 'tal:attributes="value python:pdate.year"', I get a login prompt and the page fails with the following message: [...] * Module Products.PageTemplates.ZRPythonExpr, line 47, in __call__ __traceback_info__: pdate.year * Module Python expression "pdate.year", line 1, in <expression> Unauthorized: You are not allowed to access 'year' in this context Anyone know how to avoid this? Regards, Sandor