Base plan object costing sheet

Hi,

Pls advice do v need of creating new costing sheet for base planning object separately.

We used the existing costing sheet that v already have attached to our other pricing variants because there's no difference of OH calculation. But in base plan object, it doesn't calculate the OH automatical using the given costing sheet. This is our first time of using base plan object for our price simulations, pls advice how and what should we do to get solve this prob !!!

Thanx