Solution : https://service.sap.com/sap/support/notes/62644 (SAP Service marketplace login required)
Key words : 
prerequisites solution insert form routine auswahl_setzen, additional key words plant maintenance, field selection key akth, required-entry fields, maintenance order, maintenance orders, purchase requistion, purchase requisitions, transaction omf2, purchase requisition
Related Notes : 
       
| 71537 | No PReq if required entry fields not filled in PReq |