Changing a sales order with EDI
I'm trying to change a sales orders with EDI with message type ORDCHG / IDOC type ORDERS05.
The problem i have is in identifying item to update. I thougth the field to enter VBAP-POSNR was POSEX in segment E1EDP01. But if VBAP-POSNR = 000010 and I enter 000010 in E1EDP01-POSEX the item is not changed and a new item is created.
I can use segment E1EDP19 with qualifier 002 to identify the item by vendor material number, but if I have in the sales order several items for the same material, always the 1st item with that material is updated.
Does anyone knows how to use this message type / idoc type and identify uniquely the sales order item to update ?