Consumer with message selector not working

I have a simple consumer:

            try
            {
                factory = new NMSConnectionFactory(Settings.Endpoint);

                connection = factory.CreateConnection(Settings.UserName, Settings.Password);
                connection.ClientId = Settings.Name;

                session = connection.CreateSession(AcknowledgementMode.AutoAcknowledge);
                destination = SessionUtil.GetDestination(session, Settings.QueueName, DestinationType.Queue);

                consumer = session.CreateConsumer(destination, "portCode = 'GB'", false);

                consumer.Listener += new MessageListener(OnMessage);         
            }
            catch
            {
                throw;
            }

I need to apply a selector to get messages when the portCode field is equal to "GB". This queue receives many messages.

The message is in JSON and a sample of this message is shown below:

{
  "message": {
    "list": [
      {
    xxxxxxx
      }
    ]
  },
  "header": {
    "messageCode": "xxxxxx",
    "portCode": "GB",
    "sourceSystem": "origin",
    "messageId": "ca0bf0e0-cefa-4f5a-a80a-b518e7d2f645",
    "dateTimeMessage": "2021-04-22T07:12:48.000-0300",
    "version": "1.0"
  }
}

However, I do not receive messages using the specified "GB" selector. It seems simple to define selectors, but it is not working for me.

Thanks.

Selectors do not work on the body of the message (i.e. your JSON data). They only work on the headers and properties of the message.