I have this in the class generated by wsdl.exe:

   <System.Web.Services.Protocols.SoapHeaderAttribute("ContextValue"),  _
    System.Web.Services.WebMethodAttribute(),  _
    System.Web.Services.Protocols.SoapDocumentMethodAttribute("DeleteStolenVehicle",
Use:=System.Web.Services.Description.SoapBindingUse.Literal,
ParameterStyle:=System.Web.Services.Protocols.SoapParameterStyle.Bare)>  _
   Public MustOverride Function
DeleteStolenVehicle(<System.Xml.Serialization.XmlElementAttribute([Namespace]:="http://xxxx-yyyyy.org.uk/namespaces/20061021/types")>
ByVal VehicleId As VehicleId) As
<System.Xml.Serialization.XmlElementAttribute("VehicleResponse",
[Namespace]:="http://xxxx-yyyyy.org.uk/namespaces/20061021/types")>
VehicleResponse

The I have this in my own code:

   Public Class Service
       Inherits Vehicle
   ' Add a member variable of the type deriving from SoapHeader.
   Public objMemberHeader As Context
   <WebMethod(Description:="Deletes details of a stolen vehicle.",
messagename:="DeleteStolenVehicle"), _
              SoapHeader("objMemberHeader",
Direction:=SoapHeaderDirection.In)> _
   Public Overrides Function DeleteStolenVehicle(ByVal objVehicleId As
VehicleId) As VehicleResponse
       ' For now, just an instance of the return values so we can frig it
       Dim objReturn As New VehicleResponse
       objReturn.UpdateTime = Now()
       objReturn.VehicleFraudId = 999  '*******
       Return objReturn
   End Function

When I call that, I get back exactly what Iwould expect:

   <DeleteStolenVehicleResult>
     <VehicleFraudId>999</VehicleFraudId>
     <UpdateTime>2006-10-22T10:38:38.0144535+01:00</UpdateTime>
   </DeleteStolenVehicleResult>

But as soon as I try and refer to the incoming data, for example, by
changing the asterisked line above to:

       objReturn.VehicleFraudId = objVehicleId.VehicleFraudId

I get a problem:

   <faultstring>System.Web.Services.Protocols.SoapException: Server was
unable to process request. ---&gt; System.NullReferenceException: Object
reference not set to an instance of an object.
  at Service.DeleteStolenVehicle(VehicleId objVehicleId)
  --- End of inner exception stack trace ---</faultstring>

I am probably missing something extremely simple!  What do I need to do so
that I can get hold of the incoming data?

Thanks