If you want to listen to a talkgroup, then you need to start a short call to the TG ID, so the server links it for you. It's best to have only one TG linked at a time, so call TG4000 between linking new talkgroups. You can read more about this in the user manual here:
http://manuals.sharkrf.com/openspot2/en/dmr-usage-notes.html