Magento 1.9.2.4 – Cron.php Not Working Using Cronjob Setting from Cpanel

I just set cron job using cpanel of my site,

according to that cron.php runs in every 5 mins.

But it's not.
It is working whenever I execute cron.php directly from browser.

Here is the code of my cron.php :

chdir(dirname(__FILE__));
require 'app/bootstrap.php';
require 'app/Mage.php';
if (!Mage::isInstalled()) {
    echo "Application is not installed yet, please complete install wizard first.";
   exit;
}
// Only for urls
// Don't remove this
$_SERVER['SCRIPT_NAME'] = str_replace(basename(__FILE__), 'index.php', $_SERVER['SCRIPT_NAME']);
$_SERVER['SCRIPT_FILENAME'] = str_replace(basename(__FILE__), 'index.php', $_SERVER['SCRIPT_FILENAME']);
Mage::app('admin')->setUseSessionInUrl(false);
umask(0);
$disabledFuncs = explode(',', ini_get('disable_functions'));
$isShellDisabled = is_array($disabledFuncs) ? in_array('shell_exec', $disabledFuncs) : true;
$isShellDisabled = (stripos(PHP_OS, 'win') === false) ? $isShellDisabled : true;
$isShellDisabled = true;
try {
    if (stripos(PHP_OS, 'win') === false) {
        $options = getopt('m::');
        if (isset($options['m'])) {
            if ($options['m'] == 'always') {
                 $cronMode = 'always';
            } elseif ($options['m'] == 'default') {
                 $cronMode = 'default';
            } else {
                 Mage::throwException('Unrecognized cron mode was defined');
             }
        } else if (!$isShellDisabled) {
            $fileName = escapeshellarg(basename(__FILE__));
            $cronPath = escapeshellarg(dirname(__FILE__) . '/cron.sh');

            shell_exec(escapeshellcmd("/bin/sh $cronPath $fileName -mdefault 1 > /dev/null 2>&1 &"));
            shell_exec(escapeshellcmd("/bin/sh $cronPath $fileName -malways 1 > /dev/null 2>&1 &"));
            exit;
        }
    }
    Mage::getConfig()->init()->loadEventObservers('crontab');
    Mage::app()->addEventArea('crontab');
    if ($isShellDisabled) {
        Mage::dispatchEvent('always');
        Mage::dispatchEvent('default');
    } else {
        Mage::dispatchEvent($cronMode);
    }
} catch (Exception $e) {
    Mage:: printException($e); //Please remove space after Mage:: p
    exit(1);
}

please check and let me know why its not working or call automatically, no mail send to customers when they purchase any product.