"$dn" may not work

[saturdayevening]

Hello, I try to use the LDAP Server for the lizmap authorisation. I have the following configuration in the profiles.ini.php:

searchUserBaseDN="dc=XYZ,dc=ch"
searchUserFilter="(&(objectClass=*)(mail=%%LOGIN%%))"
searchAttributes="mail:login,givenName:firstname,sn:lastname,mail:email,dn:"
bindUserDN="$dn"

searchGroupFilter="(&(objectClass=groupOfNames)(member=%%USERDN%%))"
searchGroupProperty="cn"
searchGroupBaseDN="ou=XYZ_WebGIS,dc=XYZ,dc=ch"

Unfortunately I always get this error:

ldapdao error: cannot authenticate to ldap with given bindUserDN for the login "xyz@gmail.com". Wrong DN or password

I use the following versions:

ldapdao Modul-Version: 2.2.4
Jelix-Version: 1.6.36-pre
lizmap-web-client-3.5.1
PHP Version: 7.4

It might be a problem with bindUserDN="$dn", maybe in the ldapdao.auth.php
Any idea what's wrong?