Matchcode for field EKKO-UNSEZ transaction ME31K

Experts,

I try to create a matchcode search help pair the EKKO-UNSEZ ME31K field in the transaction.

I searched a structure for the example's implementation but no success.

Before performing the transaction ME21N in the MEPOCOMM structure, here I run correctly.

Please know that I use the structure in ME31K transaction?

As I can identify the correct structure?

example

La Esquina del Abapero

Regards.