Problem with qb ak47 advanced dealership script

I had just gotten the menan ak47 advanced dealership script and put it in my server, but once i put custom vehicles (non regular GTA Vehicles) in the catalogue, and set the catalogue to buy, i go to purchase a vehicle and nothing happens, but when i put regular GTA cars in the catalogue, i can buy those. My other dealership script works fine, but this one just won’t let me purchase add on vehicles through the catalogue. Any help would be much appreciated!

I have no idea why it’s acting this way.