I'm retrieving some data from a webservice as follows

       Dim RestXML As New Data.DataSet
       Dim returnedXML As System.Xml.XmlDataDocument

       RestXML.ReadXml(functionURL)
       returnedXML = New XmlDataDocument(RestXML)

The return is something like this..

 <?xml version="1.0" encoding="utf-8" ?>
- <CallResults>
   - <ServiceOutput>
         <accountBalance>46.5</accountBalance>
         <rentalPrice>3.5</rentalPrice>
         <purchasePrice>6.5</purchasePrice>
     </ServiceOutput>
   - <ServiceResult>
     <ResultCode>01</ResultCode>
     <ResultAdvisory>message</ResultAdvisory>
     </ServiceResult>
 </CallResults>

I extract the Result code as follows

       strReturncode = returnedXML.DocumentElement.SelectSingleNode("/
CallResults/ServiceResult/ResultCode").InnerText

However with different input parameters to functionURL the XML
returned can be as follows (ServiceOutput is empty)

<?xml version="1.0" encoding="utf-8" ?>
- <CallResults>
     <ServiceOutput />
   - <ServiceResult>
         <ResultCode>00</ResultCode>
         <ResultAdvisory>Message</ResultAdvisory>
     </ServiceResult>
 </CallResults>

In this case there is a failure unless I add "/NewDataSet" to identify
which element I want to extract as follows.

       strReturncode = returnedXML.DocumentElement.SelectSingleNode("/
NewDataSet/CallResults/ServiceResult/ResultCode").InnerText

Am I retrieving the response from the web service correctly. How can I
process it so that it works whether ServiceOutput is empty or not.

Thanks for reading.