Cookie expires after 30 mins when I set longer expiring time
in my codes

I use Forms Authentication in my web application, and use the following codes to
set the expire time of cookie to 3 days.

            if( ValidateUser( txtUserName.Text , txtPassword.Text ))
            {
                HttpCookie
authenticationCookie=FormsAuthentication.GetAuthCookie(txtUserName.Text,true);
                authenticationCookie.Expires=DateTime.Now.AddDays(3);//3天
                Response.Cookies.Add(authenticationCookie);
       
Response.Redirect(FormsAuthentication.GetRedirectUrl(txtUserName.Text,true));
            }


but the actual result is: the cookie's expire time is still 30 mins which is set
in web.config instead of 3 days.

Why does this happen and how to solve it.

please help me , thank you very much!

why dont you change the valeu in web.config itself?

to vik20000in:

 because I want to allow users to custom their own expiring time of cookie.

Is there more answers?

 thanks

Is there more answers?

 thanks