If your tailgater does not work when you hook it to your exterior SAT or ANT jack either you have an amplifier in the line between the tailgater and the receiver which needs to be removed or there is a short or open somewhere in the cable between the tailgater and the receiver that needs to be tracked down.
Now, you could have a bad tailgater or receiver. I just had to replace my VIP211K after one year as it had numerous issues. I would take them to a dealer or someone that has Dish and get them tested as well.