SAP Message AD594 - Table & (no fields to append)

Diagnosis
You entered the field maintenance screen with the function Appendfields, but you did not yet define any fields to be appended. In thisstate, certain actions such as activation are not possible because thesystem is waiting for the input of fields to be appended.

Procedure
If you have no fields to be appended, terminate the function Appendfields and try again to execute the selected action.