[kronolith] alert problem

[Alain DEFRANCE]

hello,
when an alert is configured on event i've an error and no alert is sent :

Notice: Prefs_ldap : Required LDAP extension not found. in 
/usr/local/lib/php/PEAR.php on line 755

Warning: Missing argument 2 for fatal() in 
/usr/xxx/htdocs/horde/lib/Horde.php on line 159

Warning: Missing argument 3 for fatal() in 
/usr/xxxx/htdocs/horde/lib/Horde.php on line 159

my ldap is working fine what is the ldap attributes who is missing ?

thank for reply

regards