[Zope] Invalid Date-Time String error

I when trying to add a ZClass product with Date property, I keep getting an Invalid Date-Time Error. I am running Zope 2.6. This ZClass product was created back in Zope 2.4 or so. Not sure why it is happening now when it has worked in the past on earlier versions of Zope. Any ideas? Traceback (innermost last): a.. Module ZPublisher.Publish, line 98, in publish b.. Module ZPublisher.mapply, line 88, in mapply c.. Module ZPublisher.Publish, line 39, in call_object d.. Module OFS.PropertySheets, line 396, in manage_addProperty e.. Module ZPublisher.Converters, line 108, in field2date Invalid Date-Time String Thanks in advance! Chris Chris Bruce