NHibernate映射问题

我有一张像这样的桌子:

CREATE TABLE [dbo].[MOVIES_HISTORY](
 [DATE] [datetime] NOT NULL,
 [COUNT] [int] NOT NULL CONSTRAINT [DF_MOVIES_HISTORY_COUNT]  DEFAULT ((0)),
 CONSTRAINT [PK_MOVIES_HISTORY] PRIMARY KEY CLUSTERED 
(
 [DATE] ASC
)WITH (PAD_INDEX  = OFF, IGNORE_DUP_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace Kinoplex.Models
{
    public class MoviesHistory
    {
        private DateTime date;
        private int count;

        public DateTime Date
        {
            get
            {
                return date;
            }
            set
            {
                date = value;
            }
        }

        public int Count
        {
            get
            {
                return count;
            }
            set
            {
                count = value;
            }
        }
    }
}

映射文件:

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"
                   namespace="Kinoplex.Models"
                   assembly="Kinoplex">

  <class name="MoviesHistory"
         dynamic-insert="true"
         dynamic-update="true"
         lazy="false"
         table="MOVIES_HISTORY">


    <id name ="Date" column="DATE" type="datetime">
    </id>

    <property name ="Count" >
      <column name="COUNT" sql-type="int" not-null="true"></column>
    </property>



  </class>
</hibernate-mapping>

其他班都在上课,我只有这一班有问题。

执行查询,如:

IQuery query = this.session.CreateQuery("from MoviesHistory");

未映射MoviesHistory[来自MoviesHistory]

谁能告诉我怎么了?我怀疑id列可能是错误的,但找不到任何相关信息。