I have been using SM3 for appx a year now and have not been using Lot numbers. My costs are not adding up for some reason and I believe that is the reason why.... if anyone is experienced with SM3 and can help me with this issue I will be eternally grateful. It seems as though when I enter a new supply purchase the remaining supply of the same is ignored and the costs are solely based on the newly recorded purchase (if that makes any sense)....