setcookie doesn't save session properly

I'm using setcookie($sessionName, $sessionid, time()+60*60*24*10000, $sessionCookie['path'], $sessionCookie['domain'], $sessionCookie['secure']); to, obviously, store a session. The problem is that this always times out after 24 hours, and I can't figure out why. Is there something I'm missing? ie, perhaps this doesn't save a session itself, so the session still gets deleted. But then why does the session stick around for 24 hours even if the browser is closed? Sessions used to time out when the browser was closed before adding this. Also, I only use session_start() so perhaps I'm supposed to call session_id()? Thanks, Realm