add subtotal to edit order admin woocommerce

gistfile1.txt

/*
* This code will add subtotal to edit order admin woocommerce.
* Author: WooExtend
* Date: 13-02-2018
*/
add_action( 'woocommerce_admin_order_totals_after_discount', 'vp_add_sub_total', 10, 1);
function vp_add_sub_total( $order_id ) {
	$order = wc_get_order( $order_id );
	?><tr>
	<td class="label">Subtotal:</td>
	<td width="1%"></td>
	<td class="total"><?php echo wc_price($order->get_subtotal());?></td>
	</tr><?php
}