I have a Navigator III GPS, communication center, head set, mic on the K1200LT. I used Mapsource to plot a route and then told the GPS to navigate the ruote expecting the GPS to give me tirn by turn verbal instruction through the headset as to when a turn was g soming up or even re-route me if I made I wrong turn. I got neither. Why can't I hear the instructions in the headset. Why does it not instantiouslt reroute? I have the speaker on the GPS set at 30% should I go higher? I head nothing.