Dear Sumit K,
Can You please check if cost calculation function work properly at the time of Prod/ Process order?
and secondly also check if there is zero component quantity calculated in the prod/ process order and please also confirm if you are posting back-flushing/ Auto GR while confirmation.
Rates of activity type must be maintained for each activity types. If above all working fine, then you have to consult with your FI/CO consultant.
Reason can select FI document type while posting a FI/CO document. May FI consultant developed any substitution to select the document type for this transaction.
Please let me if help my answer
Regards/ Nasir Ramzan