Diagnosis
You want to reassign staff for the start date of the current link.
However the staff assignment agreements is deactivated in Customizing.

System Response
The staff reassignment activity is canceled.

Procedure
To reassign staff, you need to activate the staff assignment agreement.

Procedure for System Administration
In Customizing for Incentive and Commission Management, activate theindicator under Basic and Master Data -> Make Settings forStaff Assignment Agreement.