Failure in changing password for Horde Authentication

[Tolingo Tolinga]

Hi,

I would like very much to let my users to change their passwords from
the Horde interface but it seems that it is not possible in the latest
Kolab version that I've intalled from source.
I'm using IMP and the error message is:

"Failure in changing password for Horde Authentication: User not found"

I've search a lot in Google and the mailing list but did not found how
to enable this feature. Would you please be so kind and tell me if
this is possible?

Thank you very much