//Kontrola.php:
////////////////////////
<?php

class Kontrola
{
    public static $prijavljeniKorisnik;

    var $vrijeme = null;
}
/////////////////////////

//LogInForm, at some point in code:
if ($rezultat->num_rows == 1)
        {
            Kontrola::$prijavljeniKorisnik = $rezultat;

            Header ('Location: index.php');
        }

//index.php immediately at start checks:
if (Kontrola::$prijavljeniKorisnik == null)

It's ALWAYS null, I have determined that in LogIn it's not null before Header function, but after the Header function when Index gets loaded, it's always null. How can I save some static data between pages'