Přesměrování nefunguje - proč?

<?php
require_once '../Mobile_Detect.php';
$detect = new Mobile_Detect;
$deviceType = ($detect->isMobile() ? ($detect->isTablet() ? 'tablet' : 'phone') : 'computer');
$scriptVersion = $detect->getScriptVersion();
?>
<?php
switch ($deviceType)
{
    case "computer":
        header("Location: jetopc.php");
exit; 
    break;
    case "phone":
    case "tablet":
        header("Location: jetomobil.php");
exit; 
    break;
    
}
?>