确认电子邮件未发送

所以我有这个代码。对于一个网站，当管理员批准您成为用户时，他会单击此链接。它将帐户设置为活动状态，但我也想发送电子邮件。

<?php
error_reporting(-1);
ini_set('display_errors', 'On');
require('includes/config.php');
//collect values from the url
$memberID = trim($_GET['x']);
$active = trim($_GET['y']);
//if id is number and the active token is not empty carry on
if(is_numeric($memberID) && !empty($active)){
//update users record set the active column to Yes where the memberID and active value match the ones provided in the array
$stmt = $db->prepare("UPDATE members SET active = 'Yes' WHERE memberID = :memberID AND active = :active");
$stmt->execute(array(
    ':memberID' => $memberID,
    ':active' => $active,
));
//if the row was updated redirect the user
if($stmt->rowCount() == 1){
//redirect to login page
$stmt = $db->prepare("SELECT email FROM members WHERE memberID = :memberID");
$stmt->bindparam(':memberID', $memberID);
$stmt->execute();
$result = $stmt->fetch(PDO::FETCH_OBJ);
//send email
    $to = $result->email;
    $subject = "account actief";
    $body = "Uw account op http://www.nol-groningen.nl is actief 'n'n
    Met Vriendelijke groet,'n'n
    Website Admin";
    $additionalheaders = "From: <".SITEEMAIL.">'r'n";
    $additionalheaders .= "Reply-To: $".SITEEMAIL."";
    mail($to, $subject, $body, $additionalheaders);
header('Location: login.php?action=active');
exit;
} else {
echo "Your account could not be activated."; 
}
}
?>

在我放入电子邮件内容之前，它确实有效，现在它只是进入空白页。有谁知道我如何修复它并让它发送确认电子邮件？