[Zope] Catalogaware ZCLass and deleting

[Sven Hohage]

Hello,
I try to delete a Catalogware ZClass with subobjects that are
also ZClasses.
That's my method to delete a Class:
-->>
  <dtml-in "objectValues('ZClassPage')">
    <dtml-let x=sequence-item>    
        <dtml- if "in_work">
           <dtml-call "manage_delObjects([x.id])">
        </dtml-if>
    </dtml-let>
   </dtml-in>

But Zope answers:
           An exception occurred in a DTML method or document. 

         Error type: BadRequest
         Error value: 980785769 does not exist 
But '980785769' EXISTS in the management-interface !!  :-((


Thanks!