WCF，多个协定，就出有关问题

WCF，多个协定，就出问题
下面的wcf服务，一个协定是没有问题的，增加一个协定就出问题了。都是双工的：

[ServiceContract(CallbackContract = typeof(ISomeCallbackContract))]
    public interface IService
    {
        [OperationContract(IsOneWay = true)]  
        void DoSomething();
    }
    //用于回调的契约
    public interface ISomeCallbackContract
    {
        [OperationContract(IsOneWay = true)]
        void SomeCallbackMethod();
    }
[ServiceContract(CallbackContract = typeof(ISomeCallbackContract2))]
    public interface IService2
    {
        [OperationContract(IsOneWay = true)]
        string DoSomething2();
    }
    public interface ISomeCallbackContract2
    {
        [OperationContract(IsOneWay = true)]
        void SomeCallbackMethod2();
    }

实现类：

 [ServiceBehavior(InstanceContextMode = InstanceContextMode.PerSession, ConcurrencyMode = ConcurrencyMode.Reentrant)]
    public class MyService : IService, IService2
    {
        static List<ISomeCallbackContract> m_Callbacks = new List<ISomeCallbackContract>();
        public void DoSomething()
        {
            ISomeCallbackContract callback = OperationContext.Current.GetCallbackChannel<ISomeCallbackContract>();
            if (m_Callbacks.Contains(callback) == false)   
            {
                m_Callbacks.Add(callback);
            }
            Console.WriteLine("这句话是在服务端执行的");
            callback.SomeCallbackMethod();
        }
        public string DoSomething2()
        {
            ISomeCallbackContract2 callback = OperationContext.Current.GetCallbackChannel<ISomeCallbackContract2>();
            callback.SomeCallbackMethod2();
            return "dfdf";
        }
    }

配置文件：
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <system.web>
    <customErrors mode="Off" />
  </system.web>
  <system.serviceModel>
    <behaviors>
      <serviceBehaviors>
        <behavior name="metadataBehavior">
          <serviceMetadata httpGetEnabled="false"/>
          <serviceDebug includeExceptionDetailInFaults="true"/>
        </behavior>
      </serviceBehaviors>
    </behaviors>
    <bindings>
      <netTcpBinding>
        <binding name="netTcpBindingConfiguration">
          <readerQuotas maxDepth="64" maxStringContentLength="2147483647 " maxArrayLength="2147483647 " maxBytesPerRead="4096" maxNameTableCharCount="16384" />
          <reliableSession ordered="true" inactivityTimeout="00:10:00" enabled="false" />
          <security mode="Transport">
            <transport clientCredentialType="Windows" protectionLevel="EncryptAndSign" />
          </security>
        </binding>
      </netTcpBinding>
    </bindings>
    <services>
      <service name="Services.MyService" behaviorConfiguration="metadataBehavior">
        <endpoint address="MyService"  binding="netTcpBinding" contract="Contracts.IService" bindingConfiguration="netTcpBindingConfiguration"  />
        <endpoint address="MyService"  binding="netTcpBinding" contract="Contracts.IService2" bindingConfiguration="netTcpBindingConfiguration"  />
        <endpoint address="mex" binding="mexTcpBinding" contract="IMetadataExchange" />
        <host>
          <baseAddresses>
            <add baseAddress="net.tcp://localhost:9999/"/>
          </baseAddresses>
        </host>
      </service>
    </services>
  </system.serviceModel>
  <system.webServer>
    <modules runAllManagedModulesForAllRequests="true"/>
  </system.webServer>
</configuration>

发布到Windows服务之后，客户端不能添加服务引用：

这是唱的哪一出啊，一个协定，一个回调，就没有问题，增加一个协定和一个回调，就出问题了，，，，
什么原因这是，请问
------解决思路----------------------
    public interface IService2
    {
       [OperationContract(IsOneWay = true)]
        string DoSomething2();
    }


先改正错误，把IsOneWay去掉。
有返回值不可以是单向调用。