You can look up the referee schedule for your games HERE.
At that website you see what the referees see.
If your game is not listed there, or is not listed in the date/time/location that you are going to use, someone made a mistake and it needs to be taken care ASAP. Even if they offered to be there, there is no guarantee that they will show up. They are independent contractors, we can not force them to show up. If no referees show up at the day and time for your game, there is very little anyone can do. Please check that webpage (and solve any issues) in advance.