Make sure that you have access to the server. From the error message box copy the web service URL (e.g. http://CompanyServer:8080/CSTFS-WS/CSTFS_Service.asmx) and try to visit the page form your Web Browser.
If an Enter Network Password appears, or you get an Access Denied page, then you do not have the correct access permissions. Refer to Security Settings to learn more about how to set access permissions for the CS-Converter Server application.