无法删除我在Facebook连接后获得的Cookie

当我按下facebook注销按钮时(当我登录时会自动显示,因为我正在使用autologutlink属性)

<fb:login-button autologoutlink="true"></fb:login-button>

我还有五个Facebook Cookies: 八哥 MyApiKey_会话密钥 MyApiKey_过期 MyApiKey_用户

在我注销之后,我真的在Facebook上注销了,因为我需要再次登录Facebook.com,但是 isConnected()

var connectSession = new ConnectSession(ConfigurationManager.AppSettings["ApiKey"], ConfigurationManager.AppSettings["Secret"]);
if (connectSession.IsConnected())
{
   var api = new Api(connectSession);
   filterContext.Controller.ViewData["FBUser"] = api.Users.GetInfo();
}

首先,我不明白为什么我还可以检索用户信息,即使我不再登录,其次:我如何删除这个Cookies。以下代码不起作用:

public static void ClearFacebookCookies()
    {
        String[] shortNames = new String[] { "_user", "_session_key", "_expires", "_ss", "" };
        HttpContext currentContext = HttpContext.Current;
        if (currentContext == null)
        {
            return;
        }
        string appKey = ConfigurationManager.AppSettings["APIKey"];
        if (appKey == null)
        {
            throw new Exception("APIKey is not defined in web.config");
        }
        foreach (var name in shortNames)
        {
            string fullName = appKey + name;
            HttpCookie cookie = currentContext.Response.Cookies[fullName];
            if (cookie != null)
            {
                cookie.Value = null;
                cookie.Expires= DateTime.Now.AddDays(-1d);
            }
            HttpCookie cookieRequest = currentContext.Request.Cookies[fullName];
            if (cookieRequest != null)
            {
                cookieRequest.Value = null;
                cookieRequest.Expires = DateTime.Now.AddDays(-1d);
            }
        }
    }// end Method