Web Service Call - SoapException

[Barbara Alderton]

I need to call a custom web service, which I send a dataset to. I am writing
it in vb.net, with a Proxy server, also written in vb.net. The web service
is written in C#. I am getting the following error:

System.Web.Services.Protocols.SoapException: Server was unable to process
request. ---> System.NullReferenceException: Object reference not set to an
instance of an object. at <class>.<function name>(DataSet inDataSet) --- End
of inner exception stack trace ---

I have traced through the process, and my dataset(created by adding a
datatable to) has values just prior to the call. Why does the web service
think that the object is not set to an instance of an object? I have also
included part of the proxy code for further info.

'<remarks/>
<System.Web.Services.Protocols.SoapDocumentMethodAttribute("http://tempuri.org/<path>/<functionname>",
RequestNamespace:="http://tempuri.org/<path>",
ResponseNamespace:="http://tempuri.org/<path> ",
Use:=System.Web.Services.Description.SoapBindingUse.Literal,
ParameterStyle:=System.Web.Services.Protocols.SoapParameterStyle.Wrapped)> _
Public Function functionname(ByVal inDataset As System.Data.DataSet)
As String
Dim results() As Object = Me.Invoke("functionname", New Object()
{inDataset})
Return CType(results(0), String)
End Function

'<remarks/>
Public Function Begin<functionname>(ByVal inDataset As
System.Data.DataSet, ByVal callback As System.AsyncCallback, ByVal asyncState
As Object) As System.IAsyncResult
Return Me.BeginInvoke("functionname", New Object() {inDataset},
callback, asyncState)
End Function

'<remarks/>
Public Function End<functionname>(ByVal asyncResult As
System.IAsyncResult) As String
Dim results() As Object = Me.EndInvoke(asyncResult)
Return CType(results(0), String)
End Function