XPath default namespace hack
/// TODO: Unsatisfying hack. The XPath treats an empty prefix as the null namespace (not the default namespace).
/// To find nodes that aren't in the null namespace, but are in the default namespace, an explicitly prefixed
/// namespace must be added to the namespace manager and used within the xpath string.
XmlNamespaceManager mgr = new XmlNamespaceManager(rowNode.OwnerDocument.NameTable);
mgr.AddNamespace("xpathnullns", rowNode.NamespaceURI);
XmlNode nextPageNode = rowNode.SelectSingleNode("xpathnullns:"+nextPageXPath, mgr);