None of my WooCommerce functions are working - php

Question

Based on Go through certain WooCommerce orders, collect data and then send the results via email anwer code that is supposed to take all the WooComerce orders from yesterday total them and email them to me, but the email prints 0 for all the values.
<?php
define('WP_USE_THEMES', false);
require( dirname( __FILE__ ) . '/wp-load.php' );
// Date
$yesterday = date( 'Y-m-d', strtotime( ' -1 days ' ) );
// Args
$args = array(
'date_created' => $yesterday,
);
// Get WC orders
$orders = Wc()->wc_get_orders( $args );
// Initialize
$subtotal = 0;
$gratuity = 0;
$taxes = 0;
// NOT empty
if ( ! empty ( $orders ) ) {
foreach ( $orders as $order ) {
// DEBUG information, removed if desired
echo '<p>ID = ' . $order->get_id() . '</p>';
// Get subtotal
$subtotal += $order->get_subtotal();
// Get fees
foreach ( $order->get_fees() as $fee_id => $fee ) {
$gratuity += $fee['line_total'];
}
// Get tax
$taxes += $order->get_total_tax();
}
}
// Send e-mail
$to = 'jesse#munerismedia.com';
$subject = 'Order totals for yesterday';
$body = '<p>Subtotal = ' . $subtotal . '</p><p>Gratuity = ' . $gratuity . '</p><p>Taxes = ' . $taxes . '</p>';
$headers = array( 'Content-Type: text/html; charset=UTF-8' );
wp_mail( $to, $subject, $body, $headers );
?>
I think I might be missing a dependency or something. Btw this is a nightly running cron job.