Diagnosis
You want to change from an entity type to the assigned object type.This is not possible because the entity type has not yet been assignedto any object type.

Procedure
The entity type is assigned to an object type indirectly via a datamodel of the type business object.
First check whether the entity type is assigned to a data model of thetype business object. If not, you can create an assignment in theData Modeler.
Next, check whether the data model is assigned to an object type. Youcan maintain such an assignment in the Business Object Repository inthe basic data of the object type.
If you want to create a new object type for the data model, you canswitch directly in change mode from the data model to creating theobject type. The short description of the data model is transferredautomatically.