in your login script you miss session_start();
before setting $_SESSION
variables
also:
if (isset($_SESSION['user_id']) && $_SESSION['user_id'] == 1) {
echo " .$username .";
$_SESSION["message"]="You must be logged in to view this page";
} else {
header('Location:Login.php');
}
notice else and i changed === to == because as i saw in your var_dump it says that its string and === matches both value and type of variable