Index page not opening while using cookies in PHP , FORCE REDIRECT TO THE PAGE which should appear while logging in

I am making a simple sign up and log in page and I am stuck as i am opening index.php it opens the page which should be loaded after the person has logged in. I am using cookie to keep the user logged in.

i am using the following code so that it does not happen but it continues to happen:

if( (array_key_exists("id", $_SESSION) AND $_SESSION['id']) OR (array_key_exists("id", $_COOKIE) AND $_COOKIE['id']) ){

        header("Location: loggedIn.php");

    }

Id is my primary key. I am not seeing any errors just that the index page does not load.