Scheduling parameters are not defined for production orders

hi

i am getting this problem when i am trying to create a production order.

Scheduling parameters are not defined for production orders

No scheduling levels have been defined for production orders in Customizing for plant XXXX, order type PP01 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

how do we solve this problem.