Solution : https://service.sap.com/sap/support/notes/1028328 (SAP Service marketplace login required)
Key words : 
requested delivery date, attached correction instructions, sales data reason, sales document, changed item, terms reg_dlv_date, program error, solution implement, prerequisites
Related Notes : 
       
| 1499602 | SALES-REQ_DLV_DATE incorrect after response |