I have a Garmin GPS 276Cx.When I set up a route on automotive then view map page I find tat the route is drawn as a straight line from starting point to destination..I want to drive to destination but route doesn't use the roads available just draws a straight line.I have selected automotive in set up/system.Set activity to automobile driving in routing.Set position format to Irish IG in location.I have been through all the menus but the route will not follow the roads.
What map is on the unit?
Yes, the problem is likely the map. Not all maps are "routeable". For example, almost none of the maps on this site are capable of calculating routes.