Inmymental

Hey guys, so i did the bought a double din installation kit from amazon and installed an after market radio. Now everything works except my Navi. I understand that you lose the voice control and everything from the Navi however, the touch screen is supposed to at-least work. My Navi comes up, but when i press the "ok" button its not responsive. Someone said i was suppose to get a 80 ohm resistor or something like that but i'm not sure. Wanted to see if anyone ran into similar issue. Thanks