Been trying to auto validate invoices in odoo 10 via php for a while now with no success. Am using the below php code to validate

```
    <?php

    $url = 'http://localhost:8069';
    $url_auth = $url . '/xmlrpc/2/common';
    $url_exec = $url . '/xmlrpc/2/object';

    $db = 'DATABASE';
    $username = 'Username';
    $password = 'Password';

    require_once('ripcord/ripcord.php');
    $common = ripcord::client($url_auth);
    $uid = $common->authenticate($db, $username, $password, array());

    $models = ripcord::client("$url/xmlrpc/2/object");
    $invoice_model = 'account.invoice';
    $id = $models->exec_workflow(
           $db, $uid, $password,
                'account.invoice', 
                'invoice_open',
                2948 //invoice Id
    );

    print_r($id);

```

When I execute the above I get no results. No error message, nothing.