Solution : https://service.sap.com/sap/support/notes/35913 (SAP Service marketplace login required)
Key words : 
prerequisites program error solution corrected, additional key words va01, symptom sales documents, sales document, schedule lines, purchase requisitions, credit point, credit limit, incompleteness popup, credit management
Related Notes : 
       
| 67529 | Credit block when sales order is incomplete | 
| 53201 | Availability check during release |