at System.Xml.XPath.LogicalExpr.getValue(XPathNavigator qyContext, XPathNodeIterator iterator)
   at System.Xml.XPath.BooleanFunctions.toBoolean(XPathNavigator qyContext, XPathNodeIterator iterator)
   at System.Xml.XPath.BooleanFunctions.getValue(XPathNavigator qy, XPathNodeIterator iterator)
   at System.Xml.XPath.XPathNavigator.Evaluate(XPathExpression expr, XPathNodeIterator context)
   at System.Xml.Xsl.Processor.Evaluate(ActionFrame context, Int32 key)
   at System.Xml.Xsl.Processor.EvaluateBoolean(ActionFrame context, Int32 key)
   at System.Xml.Xsl.IfAction.Execute(Processor processor, ActionFrame frame)
   at System.Xml.Xsl.ActionFrame.Execute(Processor processor)
   at System.Xml.Xsl.Processor.Execute()
   at System.Xml.Xsl.XslTransform.Transform(XPathNavigator input, XsltArgumentList args, XmlWriter output, XmlResolver resolver)
   at System.Xml.Xsl.XslTransform.Transform(IXPathNavigable input, XsltArgumentList args, XmlWriter output, XmlResolver resolver)