Custom fields in Checkout not showing in Order page

i’ve added a few custom fiels to my checkout page, but they don’t show in the order page after being filled.

what am i doing wrong ?

/**
* Add the field to the checkout
*/
addaction( 'woocommerceafterordernotes', 'mycustomcheckout_field' );

function my_custom_checkout_field( $checkout ) {

echo '<div id="my_custom_checkout_field"><h3>' . __('Informations Passager(s)') . '</h3>';

woocommerce_form_field( 'my_field_name', array(
'type' => 'text',
'class' => array('my-field-class form-row-first'),
'label' => __('Passager 1'),
'placeholder' => __('Prénom'),
'required'  => true,
), $checkout->get_value( 'my_field_name' ));

woocommerce_form_field( 'my_field_name', array(
'type' => 'text',
'class' => array('my-field-class form-row-last'),
'placeholder' => __('Nom'),
'label' => __('(interlocuteur principal)'),
), $checkout->get_value( 'my_field_name' ));

woocommerce_form_field( 'my_field_name', array(
'type' => 'text',
'class' => array('my-field-class form-row-wide'),
'label' => __(' '),
'placeholder' => __('Numéro de passeport / CI'),
), $checkout->get_value( 'my_field_name' ));

woocommerce_form_field( 'my_field_name', array(
'type' => 'text',
'class' => array('my-field-class form-row-first'),
'label' => __('Passager 2'),
'placeholder' => __('Prénom'),
'required'  => false,
), $checkout->get_value( 'my_field_name' ));

woocommerce_form_field( 'my_field_name', array(
'type' => 'text',
'class' => array('my-field-class form-row-last'),
'placeholder' => __('Nom'),
'label' => __('(si applicable)'),
), $checkout->get_value( 'my_field_name' ));

woocommerce_form_field( 'my_field_name', array(
'type' => 'text',
'class' => array('my-field-class form-row-wide'),
'label' => __(' '),
'placeholder' => __('Numéro de passeport / CI'),
), $checkout->get_value( 'my_field_name' ));

woocommerce_form_field( 'my_field_name', array(
'type' => 'text',
'class' => array('my-field-class form-row-first'),
'label' => __('Passager 3'),
'placeholder' => __('Prénom'),
'required'  => false,
), $checkout->get_value( 'my_field_name' ));

woocommerce_form_field( 'my_field_name', array(
'type' => 'text',
'class' => array('my-field-class form-row-last'),
'placeholder' => __('Nom'),
'label' => __('(si applicable)'),
), $checkout->get_value( 'my_field_name' ));

woocommerce_form_field( 'my_field_name', array(
'type' => 'text',
'class' => array('my-field-class form-row-wide'),
'label' => __(' '),
'placeholder' => __('Numéro de passeport / CI'),
), $checkout->get_value( 'my_field_name' ));

echo '</div>';

}

/**
* Process the checkout
*/
addaction('woocommercecheckoutprocess', 'mycustomcheckoutfield_process');

function mycustomcheckoutfieldprocess() {
// Check if set, if its not set add an error.
if ( ! $POST['myfieldname'] )
wcaddnotice( _( 'Merci de compléter ces champs.' ), 'error' );
}

/**
* Update the order meta with field value
*/
add_action( 'woocommerce_checkout_update_order_meta', 'my_custom_checkout_field_update_order_meta' );

function my_custom_checkout_field_update_order_meta( $order_id ) {
if ( ! empty( $_POST['my_field_name'] ) ) {
update_post_meta( $order_id, 'Informations Passager(s)', sanitize_text_field( $_POST['my_field_name'] ) );
}
}

/**
* Display field value on the order edit page
*/
add_action( 'woocommerce_admin_order_data_after_billing_address', 'my_custom_checkout_field_display_admin_order_meta', 10, 1 );

function my_custom_checkout_field_display_admin_order_meta($order){
echo '<p><strong>'.__('Informations Passager(s)').':</strong> ' . get_post_meta( $order->id, 'Informations Passager(s)', true ) . '</p>';

Thanks in advance 🙂

https://wordpress.org/plugins/woocommerce/