Thank you watcher and Robyer, the current version of the protocol addressed the problem of the messages being received by group chats.
Robyer, now I am receiving most of the messages, but still there are some that I do not receive, I think it has something to do with the contact being on-line or not, I am not sure yet. Unfortunately, I do not use Jabber, nor ICQ. Currently, I only use Skype.