I don't understand what is your exact issue? "does not work" explains nothing.
It is better to show what you want and what was happened.
7200 means the lifetime of the session cookie. You can see the value in your browser's developer tool.
If the time has passed (in the browser's clock), the browser deletes the cookie, so the user must re-login.
But if the session data in your server is deleted, the user must re-login when the session cookie still exists.
