I want to implement a editable calendar. As a first step I installed the Calendar Tag product and followed the Jon Udell How-To almost to the letter (except for user Flintstone). I created a external method called editCalendarProperty referring to a function with the same name and a Python module Calendar.CalendarItem (CalendarItem.py was placed in a Extensions subdirectory of the Calendar product directory). Without 'date' properties the document renders fine. After editing the calendar a property is added to the document with the correct value, but the document fails to render anymore due to: Error Type: TypeError Error Value: not enough arguments for format Traceback (innermost last): File D:\Zope212\lib\python\ZPublisher\Publish.py, line 214, in publish_module File D:\Zope212\lib\python\ZPublisher\Publish.py, line 179, in publish File D:\Zope212\lib\python\Zope\__init__.py, line 202, in zpublisher_exception_hook (Object: ElementWithAttributes) File D:\Zope212\lib\python\ZPublisher\Publish.py, line 165, in publish File D:\Zope212\lib\python\ZPublisher\mapply.py, line 160, in mapply (Object: index_html) File D:\Zope212\lib\python\ZPublisher\Publish.py, line 102, in call_object (Object: index_html) File D:\Zope212\lib\python\OFS\DTMLDocument.py, line 166, in __call__ (Object: index_html) File D:\Zope212\lib\python\DocumentTemplate\DT_String.py, line 502, in __call__ (Object: index_html) File D:\Zope212\lib\python\Products\Calendar\CalendarTag.py, line 282, in render TypeError: (see above) By inspecting CalendarTag.py I have tried to figure out what might be the problem, but my Python competence is simply still not sufficient. Does anybody have a clue? tia, cb.