[Koha] Linking fields 770 and 772

Hi. I am working with serials, trying to link a parent record to a supplement record using 770 and 772 fields and it seems not to be working. In spite of using 772 0# in the supplement record and 770 0# in the parent one (using $w for linking records) no linking note appears to be displaying and no relation seems to be establishing. I´m using Koha version 19.11. I ´d greatly appreciate your feedback on this. Regards, Paola V. Cruciani