Hi,
a third approach:
Use this XPath expression
       "/x:APIInterface/x:StoreSiteResponse/x:ReturnCode
The construct the XPath object as:
        XPath xp = XPath.newInstance(xpath);
        xp.addNamespace(Namespace.getNamespace("x", "http://......."));
        Element e = (Element)xp.selectSingleNode(requestDoc);
/pmn