Diagnosis
You have not yet assigned a material type to the material groupreference material. The material type is required later, to control thescreen sequence when you use the reference material later on in thematerial master, for example.

Example
You use a different material type for fashion materials than forperishables. This ensures that the respective maintenance screens andentry processes suit the type of material being created.

Procedure
Allocate the reference material a material type which is suitable forthe majority of the materials in this material group.