Solution : https://service.sap.com/sap/support/notes/81603 (SAP Service marketplace login required)
Key words : 
additional key words subsequent settlement, check routine 'form bonusgruppe', check routine compares, integrated article maintenance, error message appears, function module me_maintain_inforecord, enter settlement groups, volume rebate group &, subsequent settlement, form routine
Related Notes : 
       
| 40147 | Collective note: Subsequent settlement (Purch.) Release 3.0 |