The cost on the Item Valuation report is different than the cost for each serial number as displayed in Serial Number Inquiry. This difference may also be seen on the I/C Serial/Lot Number Quantity On Hand Report.
The best way to reconcile the costs in IC and Serial Numbers is to firstly make them equal, and then secondly to correct them to their actual value.
There is only one place in Inventory Control where an adjustment can be made to a serialized item, without affecting the value of Inventory. This is in I/C Periodic Processing - Serial/Lot Reconciliations.
Use the Transaction Type 'Shipment' to reduce the quantity and cost of serialized items. This function will remove the cost associated with the specific serial items shipped. The cost amount reduced with a shipment entry cannot be edited. This entry does not change the Inventory value and will not create any GL entries.
Use the Transaction Type 'Receipt' to increase the quantity and cost of serialized items. Note that the Cost field refers to unit cost. This means that if a quantity of 2 are received at a cost of $10, the total cost increased is $20. As with Shipments, these entries will not change the Inventory value and will not create any GL entries. The goal of using the Shipments and Receipts is to bring the quantity and cost recorded for the serial items into alignment with the item costs in inventory.
Once all the corrections have been made to the serialized items so that their value is equal to the value recorded in Inventory, the item can be adjusted using IC Transactions / Adjustments to correct the cost and quantity of the specific item to the actual quantities and costs stored at each location.