Revaluation of PO

Dear All,

My client want to revaluate production orders at actual prices, but we have only one costing version for plan and actual. Exactly I don't know how to revaluate production orders. As we have only one version, I want to change the activity rates with actual rates in KP26 in order to revaluate the production order. But even I change no revluation is taken place. Any customizing has to be done or what is the procedure to revaluate production orders. I changed the costing version settings to allow revaluation with own business transactions.

Please help me.

ramesh b