InfoPath Dev

What is the right syntax to access use for the following Web Service data source in Jscript?

Code...I am getting an error on this

var firstName = XDocument.DOM.selectSingleNode("/dfs:myFields/dfs:dataFields/tns:UserInfoResponse/my:UserInfoResult/firstname").text

Data Source...

 myFields

   dataFields

      tns:UserInfoResponse

         UserInfoResult

             firstname

Are you using InfoPath 2007? If so, right click the field in the Data Source task pane, and click "Copy XPath". This will give you the fully qualified XPath (with the namespaces in it).

I am using Infopath 2003 so how is it done with this version?

The easiest way is to go into the XML file for the data source, and manaully create the string using the fully-qualified node names (i.e. including namespaces). It's a real pain without the new IP07 feature..