I can not figure out what the navcard does. Im in a game with 4 people and we all have it and the machine is always built in the corn feild. But everytime someone tries to put in a navcard it says [Incorrect Navcard]. I've serched the internet but i can not find any information besides were to get it or how to build the machine. I been trying for 2 days if you know anything please leave comment or make a post I fell other people are haveing the same problem.