[Zope] Verbosesecurity: "your user account is defined outside the context of the object accessed"

[Andreas Jung]

Inside a ZPT I am calling "python 
here.getTranscript().getEntry(1).getTimestamp()".
All subobjects are derived from Persistent and Implicit and are setup for 
public access
(declareObjectPublic()). The getTimestamp() method is protected by the 
'View'
permission.

When the ZPT is called then Unauthorized is raised:

Exception Value  	Your user account is defined outside the context of the 
object being accessed. Access to 'getTimestamp' of (TranscriptEntry 
instance at 933db28) denied. Your user account, admin, exists at 
/acl_users. Access requires one of the following roles: ['Manager'].

The account 'admin' is definited in /acl_users and has the Manager role
and the View permission is granted to all roles....very weird.

Any ideas?

Andreas