asp.net - Method 'XYZ' cannot be reflected

Question

We have consumed a third party web service and are trying to invoke it from an ASP.NET web application. However when I instantiate the web service the following System.InvalidOperationException exception is thrown:

Method 'ABC.XYZ' can not be reflected. System.InvalidOperationException: Method 'ABC.XYZ' can not be reflected. ---> System.InvalidOperationException: The XML element 'MyDoc' from namespace 'http://mysoftware.com/ns' references a method and a type. Change the method's message name using WebMethodAttribute or change the type's root element using the XmlRootAttribute.

From what I can gather there appears to be some ambiguity between a method and a type in the web service. Can anyone clarify the probably cause of this exception and is there anything I can do to rectify this or should I just go to the web service owners to rectify?

Edit: Visual Studio 2008 has created the proxy class. Unfortunately I can't provide a link to the wsdl as it is a web service for a locally installed thrid party app.

Answer 1

I ran into the same problem earlier today. The reason was - the class generated by Visual Studio and passed as a parameter into one of the methods did not have a default parameterless constructor. Once I have added it, the error had gone.