the waue_register-user_2.php page on your server was different from the page you sent.
i fixed the issue by changing:
$MailBody = $MailBody . "<p>Department head: ";
if($_POST["chkDeptHead"] != "") { echo ("Yes"); } else { echo("No"); }
to:
$MailBody = $MailBody . "<p>Department head: ";
$MailBody = $MailBody . ((isset($_POST["chkDeptHead"]) && $_POST["chkDeptHead"] == "1")?"Yes":"No");