编译器错误消息: CS0117: “Entity.PaperByRandomSelection”并不包含“SingleSelectionSum_1”的定义

Question

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Collections.Generic;using Entity;
using BLL;  protected void btnSave_Click(object sender, EventArgs e)
    {
        try
        {
            PaperByRandomSelection paper = new PaperByRandomSelection();
            paper.JudgeSum = Convert.ToInt32(txtJudgeSum.Text);
            paper.SingleSelectionSum = Convert.ToInt32(txtSingleSelectionSum.Text);//单选题(数)
            paper.SingleSelectionSum_1 = Convert.ToInt32(txtSingleSelectionSum_1.Text);
            paper.MultiSelectionSum = Convert.ToInt32(txtMultiSelectionSum.Text);
            ......
————————————————————————————————————————————————————————
PaperByManualSelection.cs页
————————————————————————————————————————————————————————
using System;
using System.Collections.Generic;
using System.Text;namespace Entity
{
        /// <summary>
        /// 单选题1数量
        /// </summary>
        public int SingleSelectionSum { get; set; }        /// <summary>
        /// 单选题2数量
        /// </summary>
        public int SingleSelectionSum_1 { get; set; }
        /// <summary>
        /// 单选题3数量
        /// </summary>
        public int SingleSelectionSum_2 { get; set; }
        ......——————————————————————————————————————————————————————
运行后错误提示
——————————————————————————————————————————————————————“/Web”应用程序中的服务器错误。
--------------------------------------------------------------------------------编译错误 
说明: 在编译向该请求提供服务所需资源的过程中出现错误。请检查下列特定错误详细信息并适当地修改源代码。 编译器错误消息: CS0117: “Entity.PaperByRandomSelection”并不包含“SingleSelectionSum_1”的定义源错误: 行 44:             paper.JudgeSum = Convert.ToInt32(txtJudgeSum.Text);
行 45:             paper.SingleSelectionSum = Convert.ToInt32(txtSingleSelectionSum.Text);//单选题(数)
行 46:             paper.SingleSelectionSum_1 = Convert.ToInt32(txtSingleSelectionSum_1.Text);
行 47:             paper.MultiSelectionSum = Convert.ToInt32(txtMultiSelectionSum.Text);
行 48:             paper.PaperName = txtPaperName.Text;
 源文件: c:\Users\Administrator\Documents\Visual Studio 2010\WebSites\TestOnLine10\Web\Tester\AddPaperByRandomSelection1.aspx.cs    行: 46 显示详细的编译器输出:C:\Program Files\Common Files\Microsoft Shared\DevServer\10.0> "C:\Windows\Microsoft.NET\Framework\v2.0.50727\csc.exe" ...Microsoft (R) Visual C# 2005 编译器 版本 8.00.50727.4927
用于 Microsoft (R) Windows (R) 2005 Framework 版本 2.0.50727
版权所有(C) Microsoft Corporation 2001-2005。保留所有权利。c:\Users\Administrator\Documents\Visual Studio 2010\WebSites\TestOnLine10\Web\Tester\AddPaperByRandomSelection1.aspx.cs(46,19): error CS0117: “Entity.PaperByRandomSelection”并不包含“SingleSelectionSum_1”的定义 
显示完整的编译源：
...--------------------------------------------------------------------------------
版本信息: Microsoft .NET Framework 版本:2.0.50727.4963; ASP.NET 版本:2.0.50727.4955 
小弟刚接触这种方式、请教个位高手不是在PaperByManualSelection.cs页面定义吗？为什么不管用呢？