Job receipt to Inventory - Message comes up saying at least one serial number is not matched..?

We are trying to do a job receipt to inventory for 1 piece of a 50 piece run. We select the serial number we want to use on the job receipt to inventory serial number selection screen and then click OK and we get a pop up box that says “At least 1 serial number is not matched. Continue (Y/N)”. We’ve never seen this come up before so we don’t know if we should continue or not. Does anyone know what can cause this or what we can check to make it go away?

Thanks in advance!!

Did you check to make sure that serial number doesn’t already exist in inventory?