Might have a return ticket that is billed but did not have any qty returned entered. Can happen when job is closed and then reopened.
Need to enter in a partial return ticket back dated to the last Invoice To date. These quantities should be in the carryover tab on the job screen and need to be left alone.
If any new return tickets have been created, use the recalculate button to get the correct quantity on hand, then adjust the qty to pick up and returned so they are not greater than the quantity on hand.