Message BK244 - Can't reverse material consumption at PM orders

Hello SAP Gurus,

When I reverse confirmation at iw45 transaction code for pm orders, it only reverses activity consumptions but it doesnt reverse the material consumption that I confirmed for pm order. I get this warning message below;

Message BK244 - Not possible to reverse actual costs

Diagnosis

    You have reversed the / confirmation. Actual costs are to be posted for

    this reversal, but there is no cost accounting document for this

    reversed confirmation.

System Response

    No actual costs are posted for the confirmation reversal.

How could I fix this?

Thanks a lot already

sadullah