求助当前的上下文中不存在名称

本人按照视频学习.net，遇到一个问题，显示当前上下文中不存在名称“txtUserName” 查网页说是指向两个cs文件，怎么找也没有找出来，请高手指点。如下代码不胜感激
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="注册.aspx.cs" Inherits="注册登录1.注册" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
    <title>注册用户</title>
    <style type="text/css">
        .error{background:Red;}
        .style1
        {
            height: 27px;
        }
    </style>
    <script src="js/jquery-1.8.3.js" type="text/javascript"></script>
    <script type="text/javascript">
        $(function () {
            $("#<%=txtPassword.ClientID%>").blur(function () {
                var str = $(this).val();
                if (str.length <= 6) {
                    $("#passwordLevel").text("弱");
                }
                else {
                    var regex = /\W/; //判断是否含有非字母数字
                    if (regex.test(str)) {
                        $("#passwordLevel").text("强");
                    }
                    else {
                        $("#passwordLevel").text("中");
                    }
                }
            });
            $("#<%=form1.ClientID %>").submit(function (e) {
                var pwd1 = $("#<%=txtPassword.ClientID %>").val();
                var pwd2 = $("#<%=txtPassword2.ClientID %>").val();
                if (pwd1 != pwd2) {
                    alert("两次输入的密码不一致");
                    return false;
                    e.preventDefault();
                }
                var email = $("#<%=txtEmail.ClientID %>").val();
                var regex = /.+@.+/;
                if (!regex.test(email)) {
                    alert("Email地址格式不正确");
                    return false;
                }

            });
        });
        </script>


</head>
<body>
    <form id="form1" runat="server">
    <div>

     <table>
     <tr><td>
         <asp:Label ID="Label1" runat="server" Text="用户名" AssociatedControlID="txtUserName"></asp:Label></td><td>
             <asp:TextBox ID="txtUserName" runat="server" AutoPostBack="true"
                 ontextchanged="txtUserName_TextChanged"></asp:TextBox>
             <asp:Label ID="labelUserName" runat="server" Text="Label" CssClass="error" Visible="False"></asp:Label>
         </td>
         </tr>
     <tr><td>
         <asp:Label ID="Label2" runat="server" Text="密码"></asp:Label></td><td>
             <asp:TextBox ID="txtPassword" runat="server"></asp:TextBox>密码强度:<span id="passwordLevel"></span></td></tr>
     <tr><td>
         <asp:Label ID="Label3" runat="server" Text="再次输入密码"></asp:Label></td><td>
             <asp:TextBox ID="txtPassword2" runat="server"></asp:TextBox></td></tr>
     <tr><td>
         <asp:Label ID="Label4" runat="server" Text="邮箱"></asp:Label></td><td>
             <asp:TextBox ID="txtEmail" runat="server"></asp:TextBox></td></tr>
     <tr><td class="style1">
         <asp:Button ID="btnRegister" runat="server" Text="注册"
             onclick="btnRegister_Click" />
         <asp:Label ID="Label" runat="server" Text="Label"></asp:Label>
         <asp:Label ID="Label5" runat="server" Text="Label"  Visible="False" ></asp:Label>
         </td></tr>
     </table>

    </div>
    </form>
</body>
</html>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using 注册登录1.DAL.DataSetUsersTableAdapters;

namespace 注册登录1
{
    public partial class Register : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {

        }

        protected void txtUserName_TextChanged(object sender, EventArgs e)
        {
            T_UsersTableAdapter adapter = new T_UsersTableAdapter();
            if (adapter.GetDataByUserName(txtUserName.Text).Count >= 1)
            {
                labelUserNameErrorMsg.Visible = true;
                labelUserNameErrorMsg.Text = "此用户名已存在";

            }
            else
            { labelUserNameErrorMsg.Visible = false; }

        }

        protected void btnRegister_Click(object sender, EventArgs e)
        {
            if (txtPassword.Text != txtPassword2.Text)
            {
                // Label1ErrorMsg.Text = "两次输入的密码不一致";
                // LabelErrorMsg.Visible = true;
                 Label5.Text = "两次输入的密码不一致";
            }
        }
    }
}

补充：.NET技术 ,  ASP.NET

求助 当前的上下文中不存在名称

求助当前的上下文中不存在名称