Hi Eduardo
Thanks for your prompt response.
Could you please be more specific in the solution proposed in the Post Data?
I put a breakpoint in the formula assigned in Copy requirements and the field VBUK-BUCHK is always blank.
Anyway, this is an special case because the Healthcare Industry Solution is active and the invoices are created directly in SD without an Order. They are posted with an 'X' in the field VBRK-FKTYP, that means that are invoces that belong to an interface.
Thanks again
Matías