EF无法访问LoadProperty访问的有关问题

EF无法访问LoadProperty访问的问题
程序代码如下，开发环境为VS2012 .NET + Framework 4.5 + EntityFramework 5.0

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using ConsoleApplication4.Model;

using System.Diagnostics;

using System.Data.Objects.DataClasses;



namespace ConsoleApplication4

{

    class Program

    {

        static void Main(string[] args)

        {

            NorthwindEntities db = new NorthwindEntities();

            db.Configuration.LazyLoadingEnabled = false;



            IQueryable<Employee> employees = from e in db.Employees

                                             select e;



            foreach (Employee e in employees)

            {

                db.LoadProperty(e, e => e.Orders); //编译器提示找不到LoadProperty方法

      }

            Console.ReadKey();

        }

    }

}

求解，谢谢！

------解决方案--------------------

using System.Data.Entity;