[Zope] cannot add STX Documents

[Marcus Bergmann]

Hello,

I run a new 2.6.1 version and imported the user directories and the STX 
Document product from an old 2.5.0 version (via export/import not 
copying the data.fs).
The existing STX and RSTX Documents are ok. I can view and edit them. 
But I can't add new STX or RSTX Documents.
Has anyone an idea what I'm doing wrong?

This is the traceback:

Traceback (innermost last):
   Module ZPublisher.Publish, line 98, in publish
   Module ZPublisher.mapply, line 88, in mapply
   Module ZPublisher.Publish, line 39, in call_object
   Module OFS.DTMLMethod, line 126, in __call__
   Module DocumentTemplate.DT_String, line 474, in __call__
   Module DocumentTemplate.DT_With, line 61, in render
   Module DocumentTemplate.DT_Util, line 201, in eval
    - __traceback_info__: REQUEST
   Module <string>, line 2, in f
NameError: global name 'STX_Document' is not defined


Thanks, Marcus!