[kronolith] Error retrieving free/busy information for user@domain.com: No freebusyUrl entry found

[Michael]

      Hi All:
I am experiencing a problem with "freebusyUrl" feature in
Horde/Kronolith when trying to invite attendees for the event. 
Here is the error I get: 

  Error retrieving free/busy information for u... at domain.com: No
freebusyUrl entry found"
I also have related error when accessing Free/Busy URL from the web:
http://webmail.domain.com/horde/kronolith/fb.php?c=user[2[2]]
Fatal error: Call to undefined function: output_cache_get() in
/usr/local/apache-2.0.52/htdocs/horde/lib/Horde/Cache/zps4.php on
line 32
I have patched kronolith-2.0.0 with kronolith-2.0.1 and that did not
fix the issue. In addition, horde database has a table called
kronolith_storage which contains no entries
P.S.  While searching through bugs/mailing list, I have found Ticket
ID#372 which describes simular issuies but no resolution
Could someone provide me with any hints on this?
Thanks,

Links:
------
[2] http://webmail.domain.com/horde/kronolith/fb.php?c=user[2


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