It's a mildly annoying "feature" - you need to put a default date - 2000/01/01 will work fine. Instances must be created with a date in that field. Sometimes I think it's easier to leave them as strings....same goes for int fields - must have a default.,"loren stafford" <lstaffor-@icompression.com> wrote: ,original article:http://www.egroups.com/group/zope/?start=14438,> I'm creating a brand new ZClass (called "PDFClass"). It's my first ZClass.,> I've just added the Common Instance Property Sheet (called "PDFProperties").,> Now I'm trying to add properties to that property sheet. I added one,> "string" property OK, but now when I add the "date" property "pub_date", I,> get this error:,> Invalid Date-Time String: Sorry, an error occurred,> ,> Of course, the value is invalid -- I didn't put any value in the "Value",> box, because this is a class property, and values only make sense when the,> class is instantiated, right?,> ,> Is this Zope's problem or mine? -- Dr Ross Lazarus Associate Professor and Sub-Dean for Information Technology Faculty of Medicine, Room 126A, A27, University of Sydney, Camperdown, NSW 2006, Australia Tel: (+61 2) 93514429 Mobile: +61414872482 Fax: (+61 2) 93516646 Email: rossl@med.usyd.edu.au http://www.health.usyd.edu.au/people/rossl.htm