简单WCF程序无法将参数为类的值传递到WCF端

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.ServiceModel;
using System.ServiceModel.Channels;
using System.Runtime.Serialization;
using System.ServiceModel.Description;

namespace WCFPractice
{
    [DataContract(Name = "Data")]
    public class ServiceData : IExtensibleDataObject
    {
        [DataMember(Name = "Info")]
        private string info;

        public string Info
        {
            get { return info; }
            set { info = value; }
        }
        private ExtensionDataObject extensionData;

        public ExtensionDataObject ExtensionData
        {
            get { return extensionData; }
            set { extensionData = value; }
        }
    }


    [DataContract(Name = "Data")]
    public class ClientData : IExtensibleDataObject
    {
        [DataMember(Name = "Info")]
        private string info;
        public string extraInfo;
        public string Info
        {
            get { return info; }
            set { info = value; }
        }
        private ExtensionDataObject extensionData;

        public ExtensionDataObject ExtensionData
        {
            get { return extensionData; }
            set { extensionData = value; }
        }

    }

    [ServiceContract(Name = "GO")]
    public interface IService
    {
        [OperationContract(Name = "DispInfo")]
        void MakeSense(string info);
        [OperationContract(Name = "DispEntity")]
        void MakeSense(ServiceData serviceData);
    }


    public class ServiceImplementation : IService
    {
        public void MakeSense(string info)
        {
            Console.WriteLine(info);
        }
        public void MakeSense(ServiceData serviceData)
        {
            Console.WriteLine("Info=" + serviceData.Info + "     Extra Data=" + serviceData.ExtensionData);
        }

    }


    //Name = "GO"必须与服务端设置的值一样，这样做是为了能找到该服务
    [ServiceContract(Name = "GO")]
    public interface IClient
    {
        [OperationContract(Name = "DispInfo")]
        void MakeSense(string info);
        [OperationContract(Name = "DispEntity")]
        void MakeSense(ClientData clientData);

    }


    class Program
    {
        static void Main(string[] args)
        {
            ServiceHost host = new ServiceHost(typeof(ServiceImplementation),
                               new Uri("http://localhost:8080"));//Uri随便定义
            host.AddServiceEndpoint(typeof(IService), new BasicHttpBinding(), "Make");//Make随便定义
            host.Open();
            ChannelFactory<IClient> factory = new ChannelFactory<IClient>(new BasicHttpBinding(),
                                              new EndpointAddress("http://localhost:8080/Make"));//将以上两个地址组合即可
            IClient proxy = factory.CreateChannel();
            proxy.MakeSense("Let's Go");//能正确调用
            ClientData clientData = new ClientData();
            clientData.Info = "I am Info";
            clientData.extraInfo = "I am extra info";
            proxy.MakeSense(clientData);//clientData传到WCF Service后值为空
            ((IChannel)proxy).Close();
            host.Close();
            Console.ReadKey();
        }
    }
}