Could not get results message with barcode in our collection

[jrcwiok]

We have installed WMS-Labeling on a Linux server running PHP 7.4.20. We have a WSKey for a production environment and we have set up the configuration file correctly as far as we can tell. The message we receive when we enter a barcode for an item in our collection is: Could not get results. Any help you could offer is greatly appreciated! AMNH Library Staff

config.php file contents below:
//Base folder, if any. Leave blank if site is in root web folder.
$base_url = '/labeling';
$site_title = 'AMNH WMS Labeling';
//Default page title
$page_title = 'AMNH WMS Labeling';

/*

• This variable defines the number of individual
• labels on your sheet of two column label stock.
• This is here so you can prevent waste on partially
• used label stock.
  */
  $labelStartOptions = 12;

if (defined('WSKEY') === FALSE) {
define('WSKEY', 'our production wskey');
}

if (defined('BIBKEY') === FALSE) {
define('BIBKEY', 'our production wskey');
}

if (defined('SECRET') === FALSE) {
define('SECRET', 'our production secret');
}

if (isset($inst_id) === FALSE) {
$inst_id = '86441';
}

if (defined('PRINCIPALID') === FALSE) {
define('PRINCIPALID', '8eaa9f92-3951-431c-975a-d7df26b8d131');
}

if (defined('PRINCIPALIDNS') === FALSE) {
define('PRINCIPALIDNS', 'urn:oclc:wms:da');
}

if (defined('URL') === FALSE) {
define('URL', 'https://circ.sd00.worldcat.org/LHR');
}

if (defined('BIBURL') === FALSE) {
define('BIBURL', 'http://www.worldcat.org/webservices/catalog/content');
}

if (defined('METHOD') === FALSE) {
define('METHOD', 'GET');
}

if (defined('BODYHASH') === FALSE) {
define('BODYHASH', '');
}