Over heads is not calculated for Target cost

Hi Experts,

I need a help....

We are facing a issue for Production order (ATO -Assemble to Order) target cost is not calculated for overheads. I have verified standard cost estimate was not done for the material. Reason is ATO order and WBS element with BOM. There is no fixed BOM. Can i know how it will calculate the standard cost estimate for this scenario..

Thanks in Advance..

Thanks & Regards,

Sunny...