使用PHP和Javascript不准确的最后修改时间

Both of these are displaying the wrong time. The modified time is 5:30 AM. PHP displays 12:30 PM and Javascript 10:30 (AM or PM?). It seems PHP is the way to go, but no scripts I've found are correct on my system. I'm using XAMPP and Windows XP. How would one go about displaying an accurate last modified time?

<?
$last_modified = filemtime("header.php");
    echo("last modified ");
    echo(date("m.j.y h:ia", $last_modified));
    ?>

    <script type="text/javascript">
    document.write(document.lastModified);
    </script>

try setting default time zone like UTC in below code it may help u

<?
date_default_timezone_set('UTC'); 
$last_modified = filemtime("header.php");
    echo("last modified ");
    echo(date("m.j.y h:ia", $last_modified));
    ?>

    <script type="text/javascript">
    document.write(document.lastModified);
    </script>