Order Combination in IS MILL

Hi Gurus,

Can anybody throw some light on the config steps for using Order Combination.

Actually we are using IS Mill here.

I have taken 2 materials and created 1-1 production Order for each material. But when i am going in MILL_OC transaction code, it is giving me the msg "NO PRODUCTION ORDER SELECTED".

Is order confirmation is required before doing MILL_OC.

Is there any config. which needs to be done before using this.

Please suggest.

Thanks in Advance !!

SISL