SAP Message S2L008 - Material &1 not planned in APO

Diagnosis
The MRP type maintained in the material master does notallow any external planning for material &v1&.

System Response
No requirements from APO are taken into account.

Procedure
To allow external planning for your material, you have to choose 1
or 2 as the planning method in the IMG activity CheckMRP Types. (Customizing for Materials Management ->Consumption-Based Planning -> Master Data).