.Net WSDL command line utility error

WSDL : error WSDL1: Unable to cast object of type 'System.Xml.XmlElement'
to type 'System.Web.Services.Description.ServiceDescriptionFormatExtension'.

using System.ServiceModel;

[ServiceBehavior(Name = "MyConcreteServiceName", Namespace = "http://www.mycompany.com/services/")]
public class MyConcreteService: IMyService
{
}

<wsdl:definitions name="MyConcreteServiceName" targetNamespace="http://tempuri.org/">

<wsdl:definitions name="MyConcreteServiceName" targetNamespace="http://www.mycompany.com/services/">