BAPI to update Production Order field AFPO-ANZSN

Hi there,

We are using the FM SERNR_ADD_TO_PP to add serial numbers to a Production Order using an RF scanning transaction.

All works well, the only issue is that the field AFPO-ANZSN (number of serial numbers) does not get updated.

I tried a few FMs suggested in forum to update this field, so far without success (CO_BI_AFPO_UPD does not work)

Can anyone please give a suggestion on how to successfully update this field?

Thanks,

David