The requested vessel with name GMB6 and MMSI:257999659 and IMO:0 is temporary not in our database.
Perhaps you mean one of the following ships:

Vessel name IMO MMSI In range Destination Last report
GMB 3 9698733 419000829 Oct 28, 2016 15:23 UTC

Also, you may try to find the vessel in our comprehensive Vessels Database or track this ship on the map.