[Zope] unauthorized when accessing /manage in zope 2.2.1

[Philipp Dunkel]

Hia Zopers,
I'm totally confused and I couldn't figure it out in 2 working days so here
it is:

I have a Zope Product that makes use of different nested classes.
When I create an instance of this product I always get an
"unauthorized" error when clicking the instance in the management interface
(=accessing <instance>/manage)
even if I am logged in as a manager or superuser.
The strange thing is that for example <instance>/manage_access works fine
for me.
I tried all stuph with permissions, switched acquisition on and off, added
'manage' to my permission tuple, gave everyone the right to view
management-screens and so on.
The error message says only "unauthorized"
and the traceback points to Management.py

Any Ideas?
(btw: it worked fine in 2.1.6)

thanx a lot
philipp dunkel, zReal Productions, The Hague