[olink] Stylesheets can't locate targetdoc

Hello list,

I try to use a target database for my documents with olinks. I read Bob 
Staytons instructions and created a targetset.xml document. If I process 
my documents, which contains olinks to a document versionierung, I 
always get

xsltproc --novalid  --stringparam target.database.document 
"../querverweise/targetset.xml" --stringparam current.docid  "Einstieg" 
-o index.html ../../../avaniondoc/xsl/docbook/docbook-HTMLSPLIT.xsl 
artikel.xml
Olink error: cannot locate targetdoc versionierung in sitemap

Does someone know why? The targetset.xml contains the necessary line

<document targetdoc="versionierung">...</document>

Best Regards,

Oliver Fischer