там в функции ошибка, на исправленную
public static function st3to32($steamid3)
{
if (preg_match("/\[U:1:(\d+)\]/", $steamid3)) {
$steam3 = preg_replace("/\[U:1:(\d+)\]/", "$1", $steamid3);
$A = $steam3 % 2;
$B = intval($steam3 / 2);
return "STEAM_0:" . $A ...