I don't know if Selvan S. found how to solve his problem but I think that's an error from IIS (this answer is valid if you have already checked the SAP note 1619422). Did you try to test the service in the local server ? ... for instance:
http://localhost/B1ws/webreferences/loginservice.wsdl
Remember change B1WS with your local path configuration. If you don't get anything in the local server's browser, perhaps you could get any error in the logs of the server ... maybe you find permission errors and you should go to the section "DCOM configuration for DI Server" in the B1WS Document (B1 Web Services wrapper).
Now, what about if you see how is set up the application pool for B1WS in IIS. It should be with the mode "Classic .NET AppPool" (Classic Application Pool mode). I think it should work.
If it even doesn't work, you could debug the client application together with the B1WSHttpHandler. Now, you should have in mind, in order to debug, that it needs .NET Framework 2.0 to register ASP.NET to IIS.
By the way, you would have to change the source code for WSDLGenerator for connecting to SQL Server 2012 (you can download that); in the LoginService you would have to add "<s:enumeration value="dst_MSSQL2012" />" in the element "DatabaseType".