PHP: Why does one of these three session variables always generate the same integer? [closed]

I have these three session variables in my php project, two of them always generate a random value, except for the first one, which always generates 0 no matter what. What could be the problem?

session_start();
$_SESSION["HaliV"] = rand(0, 1);
$_SESSION["ladjicaROW"] = rand(1,10)*10;
$_SESSION["ladjicaCOL"] = rand(1,10);