Apple maps directions not available

I live in Arkansas and mapped my route to a Keller Texas address and in the middle of the interstate in down town Dallas the maps cut off and would not remap my route. now I am at my location and I get the directions not available error again. What is going on? I have iPhone 6 with most recent ios systen installed. I can't tell you how frightening it is in the middle of a 5 lane freeway in rush hour to lose your directions in a town you have never been to alone. You need to find the big and fix it or remove the map featture