Replacing Nodes in an XML file

[theFLY]

Hello there, I have an XML file of structure that looks like this:

<?xml version="1.0"?>
<documents>
  <header id="1">
    <title></title>
    <prodGroup></prodGroup>
    <version>
      <major></major>
      <minor></minor>
    </version>
  </header>
  <header id="2">
    <title></title>
    <prod</prodGroup>
    <version>
      <major></major>
      <minor></minor>
    </version>
  </header>
</documents>
 

The program I am currently writting will need to replace an entire header node. This is what the replace method looks like:

Private Function SaveHeader() As Boolean
 
            'get the entire  xml file to be saved to
            Dim headerDocument As XmlDocument = FileManager.GetQAHeaderFile(m_header.ProductGroup)
        'read the appropriate Node and load it into it's class
            Dim oldHeader As QAHeader = QAHeader.Find(m_header.ProductGroup, m_header.Id)
 
            'If an old header exists, overwrite, else add new header
            If oldHeader Is Nothing Then
                headerDocument.DocumentElement.AppendChild(m_header.CreateXMLNode(headerDocument))
            Else
                'make a node out of the instance read above
                Dim oldNode As XmlNode = oldHeader.CreateXMLNode(headerDocument)
        'make a node out of the information given via form
                Dim newNode As XmlNode = m_header.CreateXMLNode(headerDocument)
                'THIS LINE HERE!
                headerDocument.ReplaceChild(newNode, oldNode)
            End If
 
            'Now the save the xml file to disk
            headerDocument.Save(FileManager.GetQAHeaderLocation(m_header.ProductGroup))
            Return True
        End Function

The problem here is that I keep getting a runtime error claiming that "The node to be removed is not a child of this node." I tried to make oldNode contain everything in <documents></documents> but then the ReplaceChild methods deletes all other <header id=""></header> nodes and I'm left with only the contents of newNode.

Allow me to give you an example. I have

<?xml version="1.0"?>
<documents>
  <header id="1">
    <title>Whut</title>
    <prodGroup>Audio &amp; Video</prodGroup>
    <version>
      <major>1</major>
      <minor>3</minor>
    </version>
  </header>
  <header id="2">
    <title>teh</title>
    <prodGroup>Audio &amp; Video</prodGroup>
    <version>
      <major>5</major>
      <minor>0</minor>
    </version>
  </header>
<header id="3">
  <title>feck!@#</title>
  <prodGroup>Audio &amp; Video</prodGroup>
  <version>
    <major>7</major>
    <minor>2</minor>
  </version>
</header>
</documents>

The user wishes to change <title>feck!@ #</title> to something a little less vulgar. Iterating thru the method presented above we have the outerXML of newNode & oldNode to read:

oldNode:
"<header id="3"><title>f eck!@#</title><prodGrou p>Audio &amp; Video</prodGroup><vers ion><major>7</major><minor>2</minor></version></header>"

newNode:
"<header id="3"><title>t ruck</title><prodGrou p>Audio &amp; Video</prodGroup><vers ion><major>1</major><minor>0</minor></version></header>"

At this time I'd like to say that regardless of what element has been changed I would like the entire contents of the appropriate <header> node to be rewritten. Is this possible and how?

Any help/suggestions are greatly appreciated. Thank you for your time and patience.