的Visual Studio 2012新的ASP Web窗体应用程序不能访问从aspx文件文本框

我刚刚创建VS 2012一个新的Web窗体应用程序，我试图让位于的Login.aspx页面中的用户名文本框的值，所有的即时得到的是名用户名不存在的当期的情况下，试图访问它在login.aspx.cs文件时...

i just created a new Web Forms application in VS 2012, i'm trying to get the value of the "UserName" textbox located in the Login.aspx page, all im getting is "the name UserName does not exist in the currect context" when trying to access it in the login.aspx.cs file...

ASPX文件：

    <%@ Page Title="Log in" Language="C#" MasterPageFile="~/Site.Master" AutoEventWireup="true" CodeBehind="Login.aspx.cs" Inherits="WebApplication1.Account.Login" %>
<%@ Register Src="~/Account/OpenAuthProviders.ascx" TagPrefix="uc" TagName="OpenAuthProviders" %>

<asp:Content runat="server" ID="BodyContent" ContentPlaceHolderID="MainContent">
    <hgroup class="title">
        <h1><%: Title %>.</h1>
    </hgroup>
    <section id="loginForm">
        <h2>Use a local account to log in.</h2>
        <asp:Login runat="server" ViewStateMode="Disabled" RenderOuterTable="false">
            <LayoutTemplate>
                <p class="validation-summary-errors">
                    <asp:Literal runat="server" ID="FailureText" />
                </p>
                <fieldset>
                    <legend>Log in Form</legend>
                    <ol>
                        <li>
                            <asp:Label runat="server" AssociatedControlID="UserName">User name</asp:Label>
                            <asp:TextBox runat="server" ID="UserName" />
                            <asp:RequiredFieldValidator runat="server" ControlToValidate="UserName" CssClass="field-validation-error" ErrorMessage="The user name field is required." />
                        </li>
                        <li>
                            <asp:Label runat="server" AssociatedControlID="Password">Password</asp:Label>
                            <asp:TextBox runat="server" ID="Password" TextMode="Password" />
                            <asp:RequiredFieldValidator runat="server" ControlToValidate="Password" CssClass="field-validation-error" ErrorMessage="The password field is required." />
                        </li>
                        <li>
                            <asp:CheckBox runat="server" ID="RememberMe" />
                            <asp:Label runat="server" AssociatedControlID="RememberMe" CssClass="checkbox">Remember me?</asp:Label>
                        </li>
                    </ol>
                    <asp:Button runat="server" CommandName="Login" Text="Log in" />
                </fieldset>
            </LayoutTemplate>
        </asp:Login>
        <p>
            <asp:HyperLink runat="server" ID="RegisterHyperLink" ViewStateMode="Disabled">Register</asp:HyperLink>
            if you don't have an account.
        </p>
    </section>

    <section id="socialLoginForm">
        <h2>Use another service to log in.</h2>
        <uc:OpenAuthProviders runat="server" ID="OpenAuthLogin" />
    </section>
</asp:Content>

在CS文件：

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

namespace WebApplication1.Account
{
    public partial class Login : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            string id = UserName.Text;
        }
    }
}

编辑：
增加了自动生成的文件aspx.designer.cs：

added the auto-generated aspx.designer.cs file:

    //------------------------------------------------------------------------------
// <auto-generated>
//     This code was generated by a tool.
//
//     Changes to this file may cause incorrect behavior and will be lost if
//     the code is regenerated. 
// </auto-generated>
//------------------------------------------------------------------------------

namespace WebApplication1.Account
{


    public partial class Login
    {

        /// <summary>
        /// RegisterHyperLink control.
        /// </summary>
        /// <remarks>
        /// Auto-generated field.
        /// To modify move field declaration from designer file to code-behind file.
        /// </remarks>
        protected global::System.Web.UI.WebControls.HyperLink RegisterHyperLink;

        /// <summary>
        /// OpenAuthLogin control.
        /// </summary>
        /// <remarks>
        /// Auto-generated field.
        /// To modify move field declaration from designer file to code-behind file.
        /// </remarks>
        protected global::WebApplication1.Account.OpenAuthProviders OpenAuthLogin;
    }
}

任何帮助将大大AP preciated。

any help would be greatly appreciated.