Ovhead calculating twice in CK11N

Hi Gurus,

In FG material is Sub-contracting Material and it have BOM and it is having one Raw material. So our requirement is Overhead should calculate on Sub-contract material as well as Raw material. I did configuration accordingly. Now then when i run the CK11N system calculating Overhead on Raw material correctly but Sub-contract material not calculating correctly.

Sub-contract Material cost = $200

Raw material cost = $100

Ex: RM 100 and Overhead 10% which is $10 correct

when cost rollup to FG = the total cost is $110 + $200 = $310 here Overhead calculating on Sub-contract M is $31 which incorrect it suppose to be $100+$200 = $300 on 10% $30....the reason Overhead only calculated on RM in lower level.

Please let me know why system is calculating differently. Is something i am missing here?