3478517 - Revenue Recogntion Error Message: AccrualMeth. assignment for fixed price project incomplete

• The revenue recognition run finishes with error message "AccrualMeth. assignment for fixed price project incomplete" for sales order item XYZ-XX (XYZ-XX represents a sales order item ID). 
• The fix-price sales order item XYZ-XX is connected to project ABC (ABC represents the project ID).  
• There are further fix-price sales order items such as DEF-DD associated with project ABC (DEF-DD represents a sales order item of another sales order connected to project ABC). 
• All fix-price sales order items associated with project ABC are assigned to accrual method 108 - Recognize using cost-to-cost project POC. 

Why does this error message still appear? 

SAP Business ByDesign

AccrualMeth. assignment for fixed price project incomplete: accrual method 108 , KBA , SRD-FIN-COR , Cost & Revenue , Problem