[horde] lsat login doesn't work

[Alain DEFRANCE]

hello,
iv'e Horde: 3.0.3 and IMP: H3 (4.0.2) installed and it's works fine,
but i've a problem with 'last login'
he is either mark "never or it's a bad timestamp

i use openldap as backends, horde is able to read "last_login" attribute 
in objectClass hordePrefs,
but système can't write the last time connection...

all other attribute (theme, time_zone, date_format...) are goods  with 
read/write in my ldap

excuses my bad english

thanks for reply

Alain DEFRANCE