Consumption accounts and entry in KE21n

Dear Experts,

My  consumption of raw materials and Cost of goods manufactured are created as cost elements, but when booking the entry will not have cost centre assigned. These entries are not flown to COPA. How do i make them flow to COPA

Also if i have to rectify this non flow for previous month, can i pass KE21n to hit copa alone

Please advise

Regards

Malathi