price difference account

Hi refer to the cases & please suggest

We have to load the Planned Delivery cost MIRO for bank Charges on materail , the Scnerio is the material is issued from the Stock,&there is no material in unrestricted use

While Simulating the MIRO for Bank Charges insted of going to price difference account, the system is determing the GL-Gain/Loss from Inventory revaluation (MR21)u201D

I have also checked the OBYC for val class 3020. Proper account has been maintained for Price Difference but it is determining Revaluation a/c MR21 while posting MIRO. Please help.