Diagnosis
You wish to switch from a data model to the assigned object type.However, this is not possible because this data model is not of thebusiness object category.

Procedure
Please check whether you are in the required data model.
If you would like to assign the data model a business object, two stepsare necessary.
First mark the field business object and save the data model.
Then go back to the object type. You switch to the Business ObjectRepository and can create the object type there. The object is createdunder the data model name and the short description of the data modelis transferred automatically.
However, it is also possible, after you have marked the field businessobject and saved, to exit the Data Modeler and start the BusinessObject Repository. Go to the change mode for the object types. There,select the appropriate object type and then switch to process basicdata, where you can create the name of the current data model in thefield BO data model.