--- openbravo/src-db/database/model/functions/C_INVOICE_CREATE.xml	2015-12-28 16:26:26.000000000 +0100
+++ openbravo/src-db/database/model/functions/C_INVOICE_CREATE.xml	2016-04-14 17:25:34.680715949 +0200
@@ -975,7 +975,7 @@
                 CASE TO_CHAR(SUBSTR(RPAD(substr(bp.InvoiceGrouping, instr(bp.InvoiceGrouping, '_') + 1), 15, '0'), 2, 1))
                   WHEN '0'
                   THEN '0'
-                  ELSE sh.C_Order_ID
+                  ELSE coalesce(sh.C_Order_ID,o.C_Order_ID)
                 END
                 ) ||'-'|| (
                 CASE TO_CHAR(SUBSTR(RPAD(substr(bp.InvoiceGrouping, instr(bp.InvoiceGrouping, '_') + 1), 15, '0'), 3, 1))