PCC Settlement Error- Product Cost Collector

Dear Experts,

I am getting the bellow error when I am performing the settlement of Product cost collector.

Transaction code: KKAS (WIP)

Error: KJ 276: No WIP at target costs could be calculated

Transaction code: KKS6 (Variance)

Error: CK 572: No valid cost estimate found.

Kindly help me what could be the reason. Is it mandatory to releasing the standard cost estimate for the header product of PCC ?

Thanks,

Naveen