additional info: krb5PrincipalName: multiple value provided

[Matthijs Mohlmann <matthijs@active2.homelinux.org>]

I'm trying to add users to my LDAP database:

active2:~# ldapadd -x -h localhost -p 389 -D
"cn=ldapadm,dc=active2,dc=homelinux,dc=org" -W -f root.ldiff
Enter LDAP Password:
adding new entry
"uid=matthijs,ou=familie,ou=users,dc=active2,dc=homelinux,dc=org"
ldapadd: update failed:
uid=matthijs,ou=familie,ou=users,dc=active2,dc=homelinux,dc=org
ldap_add: Constraint violation (19)
        additional info: krb5PrincipalName: multiple value provided
 
active2:~#

The ou's are already in the database. This is my entry i want to add:

# matthijs, active2.homelinux.org
dn: uid=matthijs,ou=familie,ou=users,dc=active2,dc=homelinux,dc=org
objectClass: top
objectClass: posixAccount
objectClass: krb5Principal
krb5PrincipalName: matthijs@ACTIVE2.HOMELINUX.ORG
cn: Unknown
sn: Unknown
uid: matthijs
uidNumber: 1002
gidNumber: 100
description: users
homeDirectory: /home/users/matthijs
loginShell: /bin/bash

This are the ou's in the database:
# active2.homelinux.org
dn: dc=active2,dc=homelinux,dc=org
objectClass: top
objectClass: dcObject
objectClass: organization
o: Familie
dc: active2
 
# users, active2.homelinux.org
dn: ou=users,dc=active2,dc=homelinux,dc=org
objectClass: Top
objectClass: organizationalUnit
description: Users
ou: users
 
# familie, users, active2.homelinux.org
dn: ou=familie,ou=users,dc=active2,dc=homelinux,dc=org
objectClass: Top
objectClass: organizationalUnit
description: Familie
ou: familie

What am i doing wrong ?