im having the same trouble of it not allowing me to hook it up
I am the creator. It is made for a gooseneck attachment only. Which attacher name is "semitrailerCar". That is what the official Gooseneck Attacher name is. If you want it to hook up to all trucks just take the "Car" out and it will hook up to all trucks.
It will not hook to a semi truck. It is made for a gooseneck only.