im looking for ways to do away with negative quantities on IC aging, mainly caused by Sales and Internal Usage. the system does not allow negatives

e.g in Jan Receipts 5, sales 10 the aging for January is -5
February issue 3 and aging in 31-60 shows -3

even though the total is correct, because it adds these up and have net effects, have best can i have these net effects per selected months or per aging of periods.