You want to create a reservation for a material component assigned to a network activity.

Some possible reasons for the missing reservation for a material component assigned to a network activity are: The indicator Reservation/Purchase Requisition indicator for the material component assigned to the activity is set to “never”, which means that no reservation or purchase requisition is created for the material component. The material is assigned to the activity as a non-stock material, which means that it does not have a stock record in inventory management and no reservation is created for it. Reference:https://help.sap.com/doc/0f069b2e08b748f1b480d4c8b46c3c49/100/en-US/6a7a9f0a6e421014e10000000a174cb4.html