Solution : https://service.sap.com/sap/support/notes/545218 (SAP Service marketplace login required)
Key words :
symptom tab page 'service', tab page service reason, activates tab page 'service', attached advance correction exists, enjoy purchase order, subcontracting items, terms me21n, urgent prerequisite, /3 support package, badi me_po_sc_srv
Related Notes :
| 634395 | FAQ: Purchase orders in the service |