Solution : https://service.sap.com/sap/support/notes/1054029 (SAP Service marketplace login required)
Key words : 
terms ehs27bsp15waehs31sp25waehs32sp14waehs2004sp17waehs2005sp10wawaste managementdisposal processingbapi_po_createbapi_po_create1ehswa_112ehswa_112_po_create_v1ehswa_112_po_bapi_convertwae02create purchase orderc$ 149, current purchase order bapi 'bapi_po_create1', purchase order bapi process type, purchase order bapi 'bapi_po_create', system issues error message, i_po_header type spec, i_po_header_add_data type spec, i_po_address type spec, e_poheader type spec, e_poheaderx type spec
Related Notes : 
       
| 1401026 | Problems with purchase order (incorrect delivery date) | 
| 1241637 | Consultation for purchase order in EHS-WA (using PO BAPIs) | 
| 1231998 | Problem w/purchase order (using current purchase order BAPI) | 
| 1121504 | EH&S Waste Management system upgrade | 
| 1111389 | Messages are missing when you use the new purcahsing BAPI | 
| 1052775 | Corrections EH&S 2.7B: Support Package 15 | 
| 878978 | Problems with locks after purchase order | 
| 187687 | BAPI_PO_CREATE and Commit Work |