[Exist-open] Demo XForms RestXQ

[<ai...@un...>]

dear gurus,
the XForms/RestXQ demo runs on my localhost:8080 eXist-db server  
without problems.
I tried to create a standalone app from it as a starting point for an  
templated XForms/RestXq app.
I initialised a new app from exide and copied the relevant files from  
the XForm/RestXQ demo, adapted the paths (modules, controller.xql,  
collection.xconf) and the controller forwarded me a nice error-page.html
(compile error for demo.html):
err:XPST0017 Function instance()  is not defined in module namespace:  
http://www.w3.org/2005/xpath-functions [at line 31, column 64]

I understand the message (instance() is an XForms function not XPath)
but I am lost finding the cause.

regards
Peter