Diagnosis
The existing material assignment to the inspection plan cannot bedeleted, because material-task list assignments still exist for themultiple specifications.

Procedure
When an inspection lot is created for an inspection plan with multiplespecifications, the system needs the material-only assignment sothat it can find and use the inspection plan. Therefore, this assignmentcannot be deleted if there are still material-task list assignments withobjects for the multiple specification.
First, delete all material-task list assignments that contain objectsfor the material specification. That is, the material-task listassignments for which an object type has been specified. Then, deletethe material-only assignment for the inspection plan.
Alternatively, you can also delete all material-task list assignments inone step.