When shipping documents and purchase orders don't align, there are usually several root causes: First, the order was modified verbally after confirmation, but the documents were not updated accordingly. Second, the exchange rate and additional charges on the commercial invoice are filled in manually on the day of shipment, creating discrepancies with the original quotation. Third, when one PI is split across multiple shipments, the packing list is recalculated each time from scratch, making it easy to miscalculate the number of boxes, especially the last one. The solution is to unify the source data for all documents: pull commercial invoice data directly from the confirmed PI, and record the actual items and box counts for each shipment batch rather than allowing manual recalculation. Performing a line-by-line comparison between the purchase order and shipping documents before shipment is the most effective final checkpoint to minimize errors.