登录验证问题，亲各位大侠帮忙看看
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using DataSet1TableAdapters;

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

  }
  protected void BtnRegister_Click(object sender, EventArgs e)
  {

  }
  protected void BtnLogin_Click(object sender, EventArgs e)
  {
  T_userTableAdapter adapter = new T_userTableAdapter();
  DataSet1.T_userDataTable users = adapter.GetDataByUserName(txtUserName.Text);
  for (int i = 0; i < users.Count; i++)
  {
  DataSet1.T_userRow user = users[0];
  if (IsPostBack)
  {
  txtUserName.Text = "";
  txtPaword.Text = "";
  }
  if (users.Count <= 0)
  {
  Response.Write("<script>alert('用户名错误')</script>");
  }
  else 
  {
  if (user.userName == txtUserName.Text)
  {
  Response.Write("<script>alert('用户名错误')</script>");
  }
  if (user.password == txtPaword.Text)
  {
  Response.Write("<script>alert('登陆成功')</script>");
  adapter.ResetErrorTime(user.ID);
  return;
  }
  if (user.errorTime >= 3)
  {
  Response.Write("<script>alert('登陆失败次数过多，禁止登陆')</script>");
  return;
  }
  else
  {
  adapter.IncErrorTime(user.ID);
  Response.Write("<script>alert('密码错误')</script>");
  return;
  }
  }
  }
  }
}
用户名验证不起作用

------解决方案--------------------
if (IsPostBack)
{
txtUserName.Text = "";
txtPaword.Text = "";
}
去掉试试
------解决方案--------------------
调试啊
------解决方案--------------------
。。。。错了在验证用户名设断点