hook not working

[Filippo]

Hello, i've try to integrate a hook function but not work:

<?php
function customAfterInvoicingHook($vars) {

    $invoiceId = $vars['invoiceid'];

    $invoiceDetails = localAPI('GetInvoice', array('invoiceid' => $invoiceId));


    $xmlContent = '<?xml version="1.0" encoding="UTF-8"?>';
    $xmlContent .= '<invoice>';
    $xmlContent .= '<invoice_id>' . $invoiceDetails['id'] . '</invoice_id>';
    $xmlContent .= '<client_id>' . $invoiceDetails['userid'] . '</client_id>';
    $xmlContent .= '</invoice>';


    $xmlFilePath = '/fatture/' . $invoiceId . '.xml';
    file_put_contents($xmlFilePath, $xmlContent);
}


add_hook('AfterInvoicingGenerateInvoiceItems', 1, 'customAfterInvoicingHook')

I put this inside /includes/hooks/custom_invoice_hook.php but when i generate invoice nothing append, no file generated, no error in the server log, can you help to fix that?

Have nice day