I did not know that we are not allowed to enter bills that we don't have.
Yesterday, I go to eat at Chick-fil-a. I get a $5 bill back. I write down the serial number, stamp it, then spend it at Walmart. So, I go home, enter this bill, I indicate that I no longer have it, and then get a message saying I can't record it, since I no longer have it.
I don't think this is fair for every situation. I think I should be able to enter a bill that I spent only within the last hour or so. The timestamp doesn't have to be exactly on the hour, anyway. I would like to think that this message referred to a longer period of time, and that entering bills you just spent, is okay.