Solution : https://service.sap.com/sap/support/notes/33103 (SAP Service marketplace login required)
Key words : 
additional key words vkm1, process sales documents, prerequisites solution corrected, desired delivery quantity, required delivery quantity, caused performance problems, confirmed quantity, credit point, availability check, program rfdkli20
Related Notes : 
       
| 53201 | Availability check during release | 
| 52272 | Availability check during release | 
| 33078 | Credit check: Blocked documents are approved | 
| 31248 | Release, another check and block, performance |