Make sure that you're using an unlocked map. If yes, there are some Garmin apps that have an additional protection of not allowing unlocked maps to be used. Some allow the workaround of renaming the map as gmap3d.img instead of gmapprom.img and it still works as a routable map. Some of the newer garmin apps do not allow that either. Then you could try replacing the executable with this one from the US app [Only registered and activated users can see links. ] Unzip and put into the garmin-nav.app folder.