Solution : https://service.sap.com/sap/support/notes/520200 (SAP Service marketplace login required)
Key words :
symptom deleting schedule lines, system responsethe schedule line, system administration------------------------------------------------------------------------message number, message class 8w, 179message short text, message long text, 180message short text, delete schedule lines, delete schedule line, po schedule line
Related Notes :
| 320392 | ME22: Changing stock category though confirmations exists |