Hi, I tried to add a new property to an existing zclass-dataskin-propertysheet programmatically with <dtml-call "item.propertysheets.Basic.manage_addProperty(id,0,type)"> but that gives me Zope Error Zope has encountered an error while publishing this resource. Error Type: Bad Request Error Value: Properties cannot be added to this property sheet The reason that I want to add a new property is: I have a folder Adress with FieldObjects (Folders) Firstname Lastname Street and so on... Each FieldObject has the attributes: type, sortorder, required and others That way I can easely add or remove FieldObjects to my Adressfolder. Now I want to do all my processing based on the FieldObjects in the folder and store the values in a ZPatternRack, I defined a Zclass for storage with a propertysheet Basic defined but empty, cause I lazy I only want to define my properties only once, by putting a FieldObject in my folder. Than at runtime I wanted to check if a property with the name of my FieldObject exists, and if not I want to addit, but that does not work see above. Is this a good idea at all ? or are there better ways to achieve this ? Mit freundlichen Grüßen Joachim Schmitz AixtraWare, Ing. Büro für Internetanwendungen Hüsgenstr. 33a, D-52457 Aldenhoven Telefon: +49-2464-8851, FAX: +49-2464-905163