Production order issue

Hi gurus,

I have faced this error while creating a prod order which is pasted below.

bold No scheduling levels have been defined for production orders in

Customizing for plant X, order type XY01 and production scheduler * .

You cannot conduct any scheduling until a selection ID for detailed

planning, rough-cut planning or production rate planning has been

entered. The selection ID determines the priority for the selection of

the routing according to the criteria task list usage, type and status.

Moreover the scheduling type must be maintained.

procedure

Maintain the scheduling parameters by entering a selection ID for

detailled planning, rough-cut planning or production rate planning and

select the scheduling type.

execute function

When i tried to click execute function system gave a message object not found or maintained.

Please advise me gurus,

Thanks.

regards,

Nathan