[bdbxml] XPATH_EVALUATION_ERROR

Hi,
 
I have a problem with query XML-documents. I can create and open
containern, put documents into the container and get documents from the
container. But when I use the query
 
collection('D:/myContainer.bdbxml')/*
 
I get the following error:
com.sleepycat.dbxml.XmlException: Error: Cannot resolve collection:
D:/myContainer.bdbxml, errcode = XPATH_EVALUATION_ERROR
 
What did I make wrong???
 
Thanks for your help.
Maike