Error in proxy when calling Web service with optional parameter

[John Harkin]

Hi,
I have a Com Server which has automation compatible data types and
have used Microsoft Soap Toolkit to generate wsdl files etc.
One of the methods i need to call has optional paramaters .
I have been able to call this using a VB client which uses the
toolkit.
However using a vb.net client with a proxy generated using add web
reference results in following error :

"An unhandled exception of type
'System.Web.Services.Protocols.SoapException' occurred in
system.web.services.dll

Additional information: SoapMapper: Restoring data into SoapMapper
anyType failed
"

Is it possible use these proxys to call method with optional
parameters.?
If so is there something i'm missing?

Regrds

JOhn