OpenLDAP Error TLS: ldap_modify: Other (e.g., implementation specific) error (80)

I got an error when importing the TLS key and certificate on OpenLDAP CentOS 7.

Below is my cers.ldif configuration:

dn: cn=config
changetype: modify
replace: olcTLSCertificateFile
olcTLSCertificateFile: /etc/openldap/certs/myldap.server.hakase.io.cert
dn: cn=config
changetype: modify
replace: olcTLSCertificateKeyFile
olcTLSCertificateKeyFile: /etc/openldap/certs/myldap.server.hakase.io.key
The command to import:
[root@hakase-ldap ~]# ldapmodify -Y EXTERNAL -H ldapi:/// -f ~/certs.ldif                                                                                                                                           
The result I get:
SASL/EXTERNAL authentication started
SASL username: gidNumber=0+uidNumber=0,cn=peercred,cn=external,cn=auth
SASL SSF: 0
modifying entry "cn=config"
ldap_modify: Other (e.g., implementation specific) error (80)
To solve this error, I just need to reordered the key first, and then the certificate.
So below the configuration.
dn: cn=config
changetype: modify
replace: olcTLSCertificateKeyFile
olcTLSCertificateKeyFile: /etc/openldap/certs/myldap.server.hakase.io.key
dn: cn=config
changetype: modify
replace: olcTLSCertificateFile
olcTLSCertificateFile: /etc/openldap/certs/myldap.server.hakase.io.cer
Import again with the command on top and below is my results.
SASL/EXTERNAL authentication started
SASL username: gidNumber=0+uidNumber=0,cn=peercred,cn=external,cn=auth
SASL SSF: 0
modifying entry "cn=config"
modifying entry "cn=config"
Solved.
ndlr.