note 48587 added to function.header

I don't know why doesn't work in my page this code: <?php // Fecha en el pasado header("Expires: Mon, 26 Jul 1997 05:00:00 GMT"); // siempre modificado header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT"); // HTTP/1.1 header("Cache-Control: no-store, no-cache, must-revalidate"); header("Cache-Control: post-check=0, pre-check=0", false); // HTTP/1.0 header("Pragma: no-cache"); ?> Because when I try to use the botton "Back" from IE I recieve this warning: the page has expired ---- Manual Page -- http://www.php.net/manual/en/function.header.php Edit -- http://master.php.net/manage/user-notes.php?action=edit+48587 Delete -- http://master.php.net/manage/user-notes.php?action=delete+48587&report=yes Reason: bad code -- http://master.php.net/manage/user-notes.php?action=delete+48587&report=yes&reason=bad+code Reason: spam -- http://master.php.net/manage/user-notes.php?action=delete+48587&report=yes&reason=spam Reason: useless example -- http://master.php.net/manage/user-notes.php?action=delete+48587&report=yes&reason=useless+example Reason: contains commercial links -- http://master.php.net/manage/user-notes.php?action=delete+48587&report=yes&reason=contains+commercial+links Reason: useless note -- http://master.php.net/manage/user-notes.php?action=delete+48587&report=yes&reason=useless+note Reject -- http://master.php.net/manage/user-notes.php?action=reject+48587&report=yes Search -- http://master.php.net/manage/user-notes.php