Shaggy is correct. The machine cannot read/validate the tickets and apply credits since it is not linked to a casino system. Every time you insert a ticket at a casino, checks the validity of the ticket (confirms it is authentic and amount is correct) then transfers those credits on to the machine. Without a back end system to validate the ticket, the machine cannot accept the ticket and apply the credits.
We have a few members on here that have designed TITO (Ticket In, Ticket Out) systems that may work with your machine. I know of 3 for sure, Brian, Bettor Slots, and Foster. Maybe check with them and see if their systems will work WTH your machine. The installation is fairly simple and cost is under $100, I believe.