Hi
First, have you run your Adjust Cost Item Entries batch job?
This updates the production cost on the FG item in some circumstances so make sure it has been run before checking costs
I assume that from your text you are using standard cost, for standard cost to work you need to do a few things,
Make sure your raw materials have a standard cost set
Use the standard cost worksheet before you do production to roll up the standard cost, this sets the standard cost on the FG item including materials and overheads
Make sure that you run the "Adjust cost item entries" batch job often (Every night or once a week is good) the longer it goes without running the longer it will take to run and the more GL entries it will change
Cheers
Nev