Diagnosis
You want to change the number assignment for the appropriation requesttype.
However, appropriation requests have already been created using thisappropriation request type.

System Response
The system does not allow changes to the number assignment ifappropriation requests already exist.
The function cannot be carried out.

Procedure
Check if it is possible to delete the existing appropriation requeststhat belong to this appropriation request type. After that you would beable to change the number assignment.
Or, create a new appropriation request type with the number assignmentyou want.