Inventory Items Total Cost on a specific date

hi,

we are working in oracle applications 11i. In Oracle Inventory we use average costing.

I am developing a report that can give us the on-hand quantity on a specific date with the total cost of items.
First I used the tables: mtl_material_transactions to get the total on-hand quantity and cst_item_cost_type to get the unit cost of each item.

As cst_item_cost_type only provides the current unit cost I am trying to find the right to columns to use from mtl_material_transactions regarding the transaction cost.

I found that for most items I can get the right total cost by using the column