処理時間のかかるリモートオブジェクトのメソッドを呼び出すとエラーになるのですが

------------------------ ServiceClass.cs ------------------------
using System;
using System.Runtime.Remoting;
using System.Runtime.Remoting.Channels;
using System.Threading;
using System.Web;

public class ServiceClass : MarshalByRefObject {
   public string GetServerString(){
      Thread.Sleep(1000 * 120);
      return "Hi";
   }
}

------------------------ Web.config ------------------------

<configuration>
   <system.runtime.remoting>
      <application>
         <service>
            <wellknown mode="Singleton" type="ServiceClass, ServiceClass" objectUri="ServiceClass.rem"/>
         </service>
         <channels>
            <channel ref="http"/>
         </channels>
      </application>
   </system.runtime.remoting>
</configuration>

------------------------ Client.cs ------------------------

using System;
using System.Collections;
using System.Diagnostics;
using System.Net;
using System.Reflection;
using System.Runtime.Remoting;
using System.Runtime.Remoting.Channels;
using System.Security.Principal;

public class Client {
   public static void Main(string[] Args){
        ServiceClass service = (ServiceClass)Activator.GetObject(typeof(ServiceClass), 
                                "http://localhost/HttpBinary/ServiceClass.rem");
        Console.WriteLine("The server says : " + service.GetServerString());
   }
}