Cookie expires after 30 mins when I set longer expiring time...

[time is life]

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!

 

[Dominick Baier]

The expiration time gets regularly overwritten bei the FormsAuthModule -
why don't use set this in the config element?

 

[time is life]

to Dominick Baier:

Because I want to allow users to custom the expiring time of their cookie.

 

[Dominick Baier]

Have a look at the source of FormsAuthenticationModule - i might be wrong
(too long ago) - but i think you will find the answer there.