Problem with document() Function

I am trying to transform 2 xml files with an xslt stylesheet to html in
a xul application but it does not work. One file I referenced with the
method document() in the xslt file and then i apply the xslt   file
with the xsltprocessor for the other:
the xslt code:
 <xsl:value-of
select="document('thalia.xml')/Items/Item/ItemAttributes/Title"/>

and the javascript code:
 var xsltProcessor = new XSLTProcessor();
          // Load the xsl file
      var xslDoc =
loadfromChrome2("chrome://metabook/content/ergebnisse.xsl");
    // import the xsl
        xsltProcessor.importStylesheet(xslDoc);
      // create  XML document
      var respon = xsltProcessor.transformToDocument(xmlDoc);

but the document referenced with the document() function is ignored
during the transformation, the result document contains only nodes from
the xml document which is not referenced with document().

And i don't know why, the xml Document thalia.xml is in the same
directory like the xslt file in chrome directory from my application. I
tried to give the xpath in teh document() absolute too, but without
succes.

document('chrome://metabook/content/thalia.xml')/Items/Item"

 and i also tried an absolute extern path, not an chrome path:

document('C:\Dokumente und
Einstellungen\Ich\Anwendungsdaten\Mozilla\Profiles\default\zbp6ecm9.slt\thalia.xml')/Items/Item

the relative path and the absolute extern path are working when I test
the xslt file with xmlspy

Do you have any ideas? What have I done wrong? 

Thanks, Ninette