SAP Message WD243 - Task '&' cannot be used as a decision task

Diagnosis
The task selected cannot be used as a decision task since itsimplementation does not correspond to the guidelines. The object typeand the method of a decision task are predefined:
Object type: 'DECISION'
Method: 'PROCESS'

System Response
The task cannot be used.

Procedure
Use a task with the predefined implementation.
Note: Copy the decision task provided. Then choose copydecision task.