Default Item Category Accounts not getting picked in Purchase Orders for Inventory Items

Dear all,

            We have defined category accounts against one catgeory. ( Different from the one defined in Organization parameters). We expect that this account should get defaulted while creating purchase order for an item belonging to the above defined category. ie. in the PO Charge Account. But this is not getting effected.

Note : We are on 12.1.3, Inventory Organization is Average Costing Enabled. The item in the PO is an inventory item.

Can you please help me in this regard.

Regards,

Anand.