logical replication problem

Hi!

Setup:

- db-server_A on port 5432
- db-server_B on port 5433

on db-server_A:
postgres=# \dRp
Liste der Publikationen
Name | Eigentümer | Alle Tabellen | Inserts | Updates | Deletes
------+------------+---------------+---------+---------+---------
mig1 | postgres | t | t | t | t

on db-server_B:
postgres=# \dRs
Liste der Subskriptionen
Name | Eigentümer | Eingeschaltet | Publikation
------+------------+---------------+-------------
sub1 | postgres | t | {mig1}

in db-server_A pg_hba.conf:
local replication postgres peer
host replication postgres 127.0.0.1/32 ident
host replication postgres ::1/128 ident

on db-server_A:
postgres# CREATE PUBLICATION mig1 FOR ALL TABLES;
CREATE PUBLICATION

the command on db-server_B:
postgres# CREATE SUBSCRIPTION sub1 CONNECTION 'host=127.0.0.1
port=5432 dbname=mydb user=postgres PUBLICATION mig1;
NOTICE: created replication slot "sub1" on publisher
CREATE SUBSCRIPTION

worked as expected.
But: instead of starting replication I find Errors within db-server_B logs:
2019-01-24 10:57:58.549 CET [28956] LOG: Apply-Worker für logische
Replikation für Subskription »sub1« hat gestartet
2019-01-24 10:57:58.553 CET [28956] FEHLER: konnte keine Daten vom
WAL-Stream empfangen: FEHLER: Publikation »mig1« existiert nicht
KONTEXT: Slot »sub1«, Ausgabe-Plugin »pgoutput«, im Callback
change, zugehörige LSN 47/B4BCA2A8
2019-01-24 10:57:58.554 CET [5982] LOG: Background-Worker »logical
replication worker« (PID 28956) beendete mit Status 1

Configuration was set on both servers to include
wal_level = logical

Any ideas why this does not work as expected? Any further ideas what
to prove on db-server_A and db-server_B?

--
Thomas