MessageHeader Methode WriteHeader

Question

Hi,

I tried to add a custom Header to a client message:

 Dim newMessage As Message = buffer.CreateMessage()
  newMessage.Headers.RemoveAt(0)
  Dim memStream As New MemoryStream()
  Dim xdw As XmlDictionaryWriter = XmlDictionaryWriter.CreateBinaryWriter(memStream)
  xdw.WriteStartElement("wsse", "Security", http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd)
  xdw.WriteStartElement("wsc", "SecurityContextToken", http://schemas.xmlsoap.org/ws/2005/02/sc)
  xdw.WriteStartElement("wsc", "Identifier", http://schemas.xmlsoap.org/ws/2005/02/sc)
  xdw.WriteString("Mytext Entry")
  xdw.WriteEndElement()
  xdw.WriteEndElement()
  xdw.WriteEndElement()
  xdw.Flush()
  Dim MyHeader As MessageHeader
  MyHeader.WriteHeader(xdw, request.Version)
  newMessage.Headers.Add(MyHeader)
  request = newMessage

I got the Methode from a Microsoft  page:
http://msdn.microsoft.com/en-us/library/ms195423(v=VS.90).aspx
But it is not working, it throws an exception: Object reference not set to an instance of an object.
at line: MyHeader.WriteHeader(xdw, request.Version)


When I used the MessageHeader.CreateHeader("Name","","")


For both versions I am happy to get an answer for solving that problem
Lothar
I could not include Prefix for the Namespace