CAS does not load attributes from ldap - ldap

Question

I tried to configure CAS (6.1) to retrieve the LDAP attributes for the Principal, but it says it has no attributes [cn] and [sn] while they are obviously there.
Config:
# auth by ldap:
cas.authn.ldap[0].type=DIRECT
cas.authn.ldap[0].ldapUrl=********
cas.authn.ldap[0].baseDn=dc=boip,dc=org
cas.authn.ldap[0].subtreeSearch=true
cas.authn.ldap[0].bindDn=*********
cas.authn.ldap[0].bindCredential=*********
cas.authn.ldap[0].dnFormat=uid=%s,ou=people,dc=boip,dc=org
cas.authn.ldap[0].useStartTls=false
cas.authn.ldap[0].connectTimeout=5000
cas.authn.ldap[0].searchFilter=cn={user}
cas.authn.ldap[0].useSsl=false
cas.authn.ldap[0].enhanceWithEntryResolver=true
cas.authn.ldap[0].principalAttributeId=uid
cas.authn.ldap[0].principalAttributeList=sn,cn
log:
2022-03-24 10:40:32,807 DEBUG [org.apereo.cas.authentication.LdapAuthenticationHandler] - <Attempting LDAP authentication for [UsernamePasswordCredential(username=dexter, source=null, customFields={})]. Authenticator pre-configured attributes are [null], additional requested attributes for this authentication request are [[uid, cn, sn]]>
2022-03-24 10:40:32,855 DEBUG [org.apereo.cas.util.BinaryAttributeAwarePooledSearchEntryResolver] - <resolve criteria=[org.ldaptive.auth.AuthenticationCriteria#1746427848::dn=uid=dexter,ou=people,dc=boip,dc=org, authenticationRequest=[org.ldaptive.auth.AuthenticationRequest#414781248::user=[org.ldaptive.auth.User#1436018205::identifier=dexter, context=null], returnAttributes=[uid, cn, sn], controls=null]]>
2022-03-24 10:40:32,859 DEBUG [org.apereo.cas.util.BinaryAttributeAwarePooledSearchEntryResolver] - <searching for entry using userFilter>
2022-03-24 10:40:32,861 DEBUG [org.apereo.cas.util.BinaryAttributeAwarePooledSearchEntryResolver] - <resolved result=[org.ldaptive.SearchResult#4303153::entries=[], references=[]] for criteria=[org.ldaptive.auth.AuthenticationCriteria#1746427848::dn=uid=dexter,ou=people,dc=boip,dc=org, authenticationRequest=[org.ldaptive.auth.AuthenticationRequest#414781248::user=[org.ldaptive.auth.User#1436018205::identifier=dexter, context=null], returnAttributes=[uid, cn, sn], controls=null]]>
2022-03-24 10:40:32,862 INFO [org.ldaptive.auth.Authenticator] - <Authentication succeeded for dn: uid=dexter,ou=people,dc=boip,dc=org>
2022-03-24 10:40:32,865 DEBUG [org.apereo.cas.authentication.LdapAuthenticationHandler] - <LDAP response: [[org.ldaptive.auth.AuthenticationResponse#2072381256::authenticationResultCode=AUTHENTICATION_HANDLER_SUCCESS, resolvedDn=uid=dexter,ou=people,dc=boip,dc=org, ldapEntry=[dn=uid=dexter,ou=people,dc=boip,dc=org[]], accountState=null, result=true, resultCode=SUCCESS, message=null, controls=[[org.ldaptive.control.PasswordPolicyControl#-350070253::criticality=false, timeBeforeExpiration=-1, graceAuthNsRemaining=-1, error=null]]]]>
2022-03-24 10:40:32,865 DEBUG [org.apereo.cas.authentication.LdapAuthenticationHandler] - <Attempting to examine and handle LDAP password policy via [DefaultPasswordPolicyHandlingStrategy]>
2022-03-24 10:40:32,865 DEBUG [org.apereo.cas.authentication.support.password.DefaultPasswordPolicyHandlingStrategy] - <Applying password policy [[org.ldaptive.auth.AuthenticationResponse#2072381256::authenticationResultCode=AUTHENTICATION_HANDLER_SUCCESS, resolvedDn=uid=dexter,ou=people,dc=boip,dc=org, ldapEntry=[dn=uid=dexter,ou=people,dc=boip,dc=org[]], accountState=null, result=true, resultCode=SUCCESS, message=null, controls=[[org.ldaptive.control.PasswordPolicyControl#-350070253::criticality=false, timeBeforeExpiration=-1, graceAuthNsRemaining=-1, error=null]]]] to [org.apereo.cas.authentication.support.DefaultLdapAccountStateHandler#114ba12b]>
2022-03-24 10:40:32,865 DEBUG [org.apereo.cas.authentication.support.DefaultLdapAccountStateHandler] - <Attempting to handle LDAP account state for [[org.ldaptive.auth.AuthenticationResponse#2072381256::authenticationResultCode=AUTHENTICATION_HANDLER_SUCCESS, resolvedDn=uid=dexter,ou=people,dc=boip,dc=org, ldapEntry=[dn=uid=dexter,ou=people,dc=boip,dc=org[]], accountState=null, result=true, resultCode=SUCCESS, message=null, controls=[[org.ldaptive.control.PasswordPolicyControl#-350070253::criticality=false, timeBeforeExpiration=-1, graceAuthNsRemaining=-1, error=null]]]]>
2022-03-24 10:40:32,865 DEBUG [org.apereo.cas.authentication.support.DefaultLdapAccountStateHandler] - <Account state not defined. Returning empty list of messages.>
2022-03-24 10:40:32,865 DEBUG [org.apereo.cas.authentication.LdapAuthenticationHandler] - <LDAP response returned a result [[dn=uid=dexter,ou=people,dc=boip,dc=org[]]], creating the final LDAP principal>
2022-03-24 10:40:32,865 DEBUG [org.apereo.cas.authentication.LdapAuthenticationHandler] - <Creating LDAP principal for [dexter] based on [uid=dexter,ou=people,dc=boip,dc=org] and attributes [[]]>
2022-03-24 10:40:32,865 WARN [org.apereo.cas.authentication.LdapAuthenticationHandler] - <The principal id attribute [uid] is not found. CAS cannot construct the final authenticated principal if it's unable to locate the attribute that is designated as the principal id. Attributes available on the LDAP entry are [[]]. Since principal id attribute is not available, CAS will fall back to construct the principal based on the provided user id: [dexter]>
2022-03-24 10:40:32,865 DEBUG [org.apereo.cas.authentication.LdapAuthenticationHandler] - <LDAP principal identifier created is [dexter]>
2022-03-24 10:40:32,866 DEBUG [org.apereo.cas.authentication.LdapAuthenticationHandler] - <The following attributes are requested to be retrieved and mapped: [[]]>
2022-03-24 10:40:32,866 WARN [org.apereo.cas.authentication.LdapAuthenticationHandler] - <Requested LDAP attribute [cn] could not be found on the resolved LDAP entry for [uid=dexter,ou=people,dc=boip,dc=org]>
2022-03-24 10:40:32,866 WARN [org.apereo.cas.authentication.LdapAuthenticationHandler] - <Requested LDAP attribute [sn] could not be found on the resolved LDAP entry for [uid=dexter,ou=people,dc=boip,dc=org]>
2022-03-24 10:40:32,866 DEBUG [org.apereo.cas.authentication.LdapAuthenticationHandler] - <Created LDAP principal for id [dexter] and [0] attributes>
LDAP:
I was expecting the values 'Dexter Morgan' en 'Morgan' to be returned for cn and sn respectively.
Can anybody hint on what i might be missing here?
Thank you for reading :)
Willem.