[horde] Login only in IMP?

[Sebastian Just]

Hi!

I installed Horde 2.2.6 with IMP 3.2.3 and Kronolith 1.1.2. (Debian Sid 
with apt-get).

I played around with the differen auth-methods but I get always the same 
result:
I go to http://myserver/horde2 and the loginscreen appears.
I'm unable  to login to horde/kronolith.
I alway get a redirect the the login screen and the user and pw-field 
are blank again.

I can only login in IMP with my IMAP-user+pw (by the navbar at the bottom).
After this I can only move around in the IMP-part of horde.
Changing to another part of horde by the navbar at the bottom kills my 
session (?) and I get again everywhere the loginscreen (but can relogin 
into IMP, but not to the other parts (redirect)).
In the log I found only successful logins. :-(

I have no idea why this happens, but I found something:
The IMP-login-page opens /imp/?Horde2=asdfln34kjbnsd8934andsoon
The other login-pages open /imp/login.php?Horde2=aasdf34234andsoon
and here is the hidden URL in the forumlar empty(!).

I hope somebody has a hint for me.
Or is this a Debian-related problem?

Greets
Sebastian