Stock Balance as at 01/09/2001 = 10 and weighted average = 4.50 Stock operation Action Date Qty CPU Wegithed Average StockIn 01/09/2001 5 4.40 ((10*4.5) + (5*4.4)) / 15 = 4.4667 Sales 01/09/2001 1WHen I try to calc the qty of the item backdated, i will get balance stock = 14 becoz one of them had been sold. However, the actual qty at the time stockin should be 15. It may effect the result of weighted average. SInce invoice doesn't contain of time field, how could I know stock in was being done before sales?