Outlook 2002 does not fetch freebusy URL

[ogo2]

Hi,

I am trying to get freebusy to work with two PCs both running outlook 2002.

On the first PC the other user's freebusy information can be seen.

On the second PC no freebusy information can be seen. Neither of the
other user, nor from the local user himself if I insert his own address
into the participant list.

In /kolab/var/apache/log/apache-access.log I see that the first PC (with
working freebusy) frequently accesses the other users *.ifb file.

The 2nd PC with non-working freebusy never accesses any ifb-file. Why?

(Both PCs sometimes access files named Calendar.pfb. Perhaps related to
calendar sharing).

On both PCs I have imported the cacert.cer file. Both PCs don't complain
  regarding certificates.

The docs talk about a service pack 1 for outlook 2003 related to
certificate handling. We have outlook 2002 - is there any service fix
necessary?

Strange thing is that the working outlook is the older one:
The PC with working freebusy has outlook version 2002 (10.2627.2625)
The PC with defunct freebusy has outlook version 2002 (10.6822.6830) SP3

I entered the freebusy URL the same way on both installations and
followed the proko-instructions.

Any ideas what I can do to get it working?

Joachim