判断验证码出错！ - 编程论坛

我新学的想写登陆界面网上找到了图片验证码的代码那个已经正常条用但是判断验证码出错你们看看代码吧
session 和文本框的值都一样但是就不提示验证码正确那个提示代码贴着了你们看看吧

程序代码：

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Linq;
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.Xml.Linq;

public partial class admin_Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        string xinxi = Session["ValidateCode"].ToString();
       string xinxi1=TextBox3.Text;
       MsgBox(xinxi1);
        if (TextBox1.Text == "" || TextBox2.Text == "" || TextBox3.Text == "")
        {
            MsgBox("Uqur lar ni kuruk koy mang!");

        }
        else
        {

            if (xinxi == xinxi1)
           {
               MsgBox("验证吗正确！");
           }
           else
           {

           }

        }
        MsgBox(xinxi);

    }
    public void MsgBox(string strMsg)
    {
        string StrScript;
        StrScript = ("<script language=javascript>");
        StrScript += ("alert('" + strMsg + "');");

        StrScript += ("</script>");
        System.Web.HttpContext.Current.Response.Write(StrScript);
    }


}