How can I use {lanman} correctly?

[Frittella Laurento <laurento.frittella@gmail.com>]

I'm trying to use a lanman hash to auth my users, for example I'm trying
with something like this:
  dn:mail=dude@example.com,dc=example,dc=com
  changetype: modify
  replace: userPassword
  userPassword: {lanman}5f08db99e1768ee5a91e999999c3ac6e

I'm sure about the password but the user 'dude' cannot auth, slapd logs
this:
  slapd[11684]: conn=1 op=17 RESULT tag=97 err=49 text=


Regards,
Laurento