how to show customer email address on the EZ-Pages in Zen Cart?

I Have codes as blow, but when I write them in EZ-page as code. php will not run, please help. thanks.

<?PHP
// Query the database for customers email address by (logged in) customer's ID
$email_results = $db->Execute('SELECT customers_email_address FROM customers WHERE 
customers_id = ' . $_SESSION['customer_id']);

// The customer's Email Address is now in the PHP variable $email_addr
$email_addr = $email_results->fields['customers_email_address'];
echo $email_addr;
?>