Production confirmation value -Reg

I have the following scenario,

I got a production order for 10 pcs that needs to be confirmed. When I confirm the order using co11n, it should calculate the total price as Rs.20(moving average price for 1pc = 2 rs)

But it is caluculating 25 rs.I dont know from where it is picking the material value.

Other activity costs and overhead costs, it is caluculating properly.(Both in plan and actual values).

I am trying to debug the program. but couldnot able to find the respective tables and subroutine where I need to check exactly.

Please help me ASAP.

Thanks a lot in advance,

Regards

Rajaram