Way to our next destination

We go with the help of a Garmin GPS-navigator, but it does not help to find the right track. A track seems to the wrong direction could be the right one and if we go a track which looks going to the direction which shows to be right can turn to the wrong one after many many kilometers.
So it was happen that we went the wrong way for more than 40 km and could not reach our overnight camp we planed to go. Driving in the night in Mongolia is extreme dangerous.