[ingo] authentification problems with custom horde setup

[it at helios-media.com]

Hi,
I'm running Horde/Ingo configuration with multiple IMAP servers 
containing users mailboxes. therefore i changed the horde login script 
to obtain user information via ldap from my active directory and then 
reroute the login request to connect to the correct server. the two imap 
servers have different subnets. my problem:

if i connect to the imap-server on which horde and ingo is locally 
running everything works fine and i am able to activate and deactivate 
ingo sieve scripts in the horde webui.
when i connect to the second imap server i am able to read and write 
mails, update my dates and tasks. but when it comes to activating the 
vacation filter it tells me an "authentification error" as a driver 
response.
could anyone explain how exactly ingo authenticates with timsieved and 
which login data is used?

-- 
Matthias Herzog
Administration / IT