Call VQ and tell them the problem. Even if you bought the part used, they will probably send you a replacement for nothing. In the meantime, I'd pull the other screw and see if it will thread into the empty threaded hole. If it's the same size, or even if it's not, I'd take that screw and the trigger to a bolt and screw specialty store. We have two in my area. They should be able to gauge the size of the screw and sell you another of the same size and slightly shorter or longer as might be needed.