退出时清空Cookies的有关问题

退出时清空Cookies的问题
我在登陆页中保存了COOKIES
Response.Cookies[ "TrueName "].Value   =   sdr[ "TrueName "].ToString();
Response.Cookies[ "TrueName "].Expires   =   DateTime.Now.AddMinutes(30);

过期时间为30分钟

在退出页的Page_Load事件中
Response.Cookies.Clear();
这样我在其他页还是可以读出Cookies值，怎么回事呢？

后来我又写成下面这样
Response.Cookies[ "TrueName "].Value   =   " ";
Response.Cookies.Clear();

结果还是一样，在其他页还是可以读出Cookies的值，为什么清空不掉呢？

[解决办法]
加入Cookie:

HttpCookie cookie = new HttpCookie( "MyCookie ");

cookie1.Values.Add( "TrueName ",sdr[ "TrueName "].ToString());

Response.Cookies.Add(cookie);

======================================

注销的时候:
HttpCookie cookie = Request.Cookies[ "MyCookie "];
cookie.Expires = DateTime.Now.AddDays(-1);
Response.Cookies.Add(cookie);

[解决办法]
/// <summary>
/// 删除cookie,传值cookiename
/// </summary>
/// <param name= "cookiename "> </param>
public void delcookie(string cookiename)
{
HttpCookie cookie = new HttpCookie( " "+ cookiename + " ", null);
cookie.Expires = DateTime.Now.AddDays(-1);
System.Web.HttpContext.Current.Response.Cookies.Add(cookie);
System.Web.HttpContext.Current.Response.Cookies.Remove( "cookie ");
}