Solution : https://service.sap.com/sap/support/notes/192056 (SAP Service marketplace login required)
Key words : 
attached source code corrections, sales document entry, additional key words, route correctly, error occurs, shipping point, original route, solution implement, prerequisites, determines
Related Notes : 
       
| 321021 | Unwanted redetermination of the route | 
| 214563 | Unreq.shipping point redeterminatn with SH change | 
| 207135 | Incorrect shipping point determination in VA01 |