[horde] Error with LDAP

["Wirtel, Stéphane"]

Hi all, 

I have a warning with ldap and horde/imp.

I get this error : 

Warning: LDAP: modify operation could not be completed. in
/var/www/html/horde/libs/Prefs/ldap.php on line 470
Warning: Cannot add header information - headers already sent by (output
started at /var/www/html/horde/lib/Prefs/ldap.php:470) 
in /var/www/html/horde/imp/redirect.php on line 103

In my ldap server, the access for the 'self' or 'users' to the the
hordePrefs and others Prefs is write.

Would somebody have already had this error?

Thanks, 

Stephane