How to adjust cost an item after ran create accounting in final mode

Hi all,

I am using oracle EBS R12.1.3, and I ran create accounting in Final mode and already post to GL in period 12-2015. However, I want to adjust some item cost in this period again. I adjusted item cost in the Actual Cost Adjustment (with type = Unit cost adjustment). After that I ran Actual Cost Process -> cost update -> OPM Accounting Preprocessor -> create accounting. The item cost in period 12-2015 has updated, but when I create an inventory transaction in period 01-2016 the system did not take item cost after adjust in period 12-2015, it only take item