server work but strange log

[zorg]

Hello,
I have diiferent server
but the last one i have installed seem to work without any problem but
I have this log which appear all the time
don't really know what is it and how to get rid of this

here is the log
Dec 13 10:48:25 server cyrus/imapd[21129]: _sasl_plugin_load failed on 
sasl_server_plug_init for plugin: kerberos4
Dec 13 10:48:32 server cyrus/imapd[21130]: server add_plugin entry_point 
error generic failure

here is my imap.conf

configdirectory: /var/lib/cyrus
defaultpartition: default
partition-default: /var/spool/cyrus/mail
partition-news: /var/spool/cyrus/news
newsspool: /var/spool/news
altnamespace: no
unixhierarchysep: yes
admins: cyrus
allowanonymouslogin: no
popminpoll: 1
autocreatequota: 0
umask: 077
sieveusehomedir: false
sievedir: /var/spool/sieve
hashimapspool: true
allowplaintext: yes
sasl_mech_list: PLAIN
sasl_pwcheck_method: saslauthd
sasl_auto_transition: no
tls_cert_file: /var/lib/cety/imap.fontaine38.fr.crt
tls_key_file: /var/lib/cety/imap.fontaine38.fr.key
tls_ca_file: /var/lib/cety/imap.fontaine38.fr.csr
tls_ca_path: /etc/ssl/certs
tls_session_timeout: 1440
tls_cipher_list: TLSv1:SSLv3:SSLv2:!NULL:!EXPORT:!DES:!LOW:@STRENGTH
lmtpsocket: /var/run/cyrus/socket/lmtp
idlesocket: /var/run/cyrus/socket/idle
notifysocket: /var/run/cyrus/socket/notify