We have a small batch of checks with a different series of check numbers from our main checks.  These checks are typically handwritten for misc small items at our different office locations.  We manually enter these checks into Netsuite.

Just recently when entering the check number for one of these checks into NS, an error message popped up saying the check number had already been used, please use the next number in series. However when I search to see what the check was entered for I cannot find anything.

Why would I get the error message if indeed there is not another check in the system with that number?