Hello, There is problem with Kolab_Freebusy 1.5.0 or Kolab_Server 0.5.0 pear package. In file FreeBusy/Cache.php on line 377 there is $groups = $access->user_object->getGroupAddresses(); but on Kolab_Server package there is no Horde_Kolab_Server_Object_user::getGroupAddresses() such method.