Solution : https://service.sap.com/sap/support/notes/1045870 (SAP Service marketplace login required)
Key words :
system issues error message fkkfmchk 008, system issues error message fkkfmchk 002, business partner line item, processes error message fkkfmchk 008, service charge settlementreceivables postingsimulation, service charge settlement, fm account assignments, fm account assignment, functional area reason, error message