[Zope] Manage-clone and anonymous role

[Sven Hohage]

Hello,
I like anonymous users to add postings.
For  adding postings I use the Zope Book python-script with proxy-role
manager
->zeit = context.ZopeTime()
->id = str(int(zeit))
->exhibit=context.manage_clone(container.exhibitTemplate,id)
->exhibit.manage_changeProperties(title=title,ersteller=ersteller,erstellung
sdatum=erstellungsdatum,email=email,text=text)

But the anonymous user always gets:

  File Script (Python), line 11, in addPost
  File C:\Zopa\lib\python\OFS\CopySupport.py, line 333, in manage_clone
    (Object: Traversable)
  File C:\Zopa\lib\python\OFS\CopySupport.py, line 414, in
_verifyObjectPaste
    (Object: Traversable)
Unauthorized: Add Folders

What could be the problem??
Thanks.