[Zope] Updating Zclass object titles

Hello all, I am trying to edit an instance of a ZClass to update the title. I am using the dtml- <dtml-call "doc.propertysheets.Basic.manage_changeProperties(REQUEST)"> where this is in the submit form of a HTML form, with "title" as a field. This will update all properties except the title. I have l also tried directly updating it by calling <dtml-call "doc.propertysheets.Basic.manage_changeProperties(title=new_title)"> I have tried trapping exceptions, and neither of these calls raise one. So does anybody know what's the deal? Sherman