>Please, try the following code and see if it works:
>
>

>LOCAL lcXML  as String
>LOCAL loDOM  as MSXML2.DOMDocument
>LOCAL loNode as MSXML2.IXMLDOMNode
>
>TEXT TO lcXML TEXTMERGE NOSHOW PRETEXT 1+2+4
>  <EnteteHere xmlns="http://tempuri.org/MyHeader">
>     <FirstNode>20040118182337229</FirstNode>
>  </EnteteHere>
>ENDTEXT
>
>loDOM = CREATEOBJECT("MSXML2.DOMDocument.4.0")
>loDOM.loadXML(lcXML)
>
>loDOM.setProperty("SelectionNamespaces", "xmlns:x='http://tempuri.org/MyHeader'")
>loNode = loDOM.selectSingleNode("/x:EnteteHere/x:FirstNode")
>
>MESSAGEBOX(loNode.Text)
>
>STORE null TO loNode, loDOM
>

>
>Notice that I prefixed your elements with a Namespace prefix of "x" in order to fulfill the XPath requirement.

Ok, that works. But, that header is created by a SOAP header such as:

toSerializer.startHeaderElement('EnteteHere','http://tempuri.org/MyHeader')

I can't find a way to plug that in there. Also, the client has specific requirements for sending that header. I don't think I can modify that.