diff --git a/plugins/calendar/drivers/database/database_driver.php b/plugins/calendar/drivers/database/database_driver.php
index 44f6bd6c..9e3e05a0 100644
--- a/plugins/calendar/drivers/database/database_driver.php
+++ b/plugins/calendar/drivers/database/database_driver.php
@@ -556,7 +556,7 @@ class database_driver extends calendar_driver
         
         // stop adding events for inifinite recurrence after 20 years
         $count = 0;
-        if (++$count > 999 || (!$recurrence->recurEnd && !$recurrence->recurCount && $next->year > date('Y') + 20))
+        if (++$count > 999 || (!$recurrence->recurEnd && !$recurrence->recurCount && $next_start->format('Y') > date('Y') + 20))
           break;
       }
     }
@@ -632,7 +632,7 @@ class database_driver extends calendar_driver
             $update_master = true;
             
             // delete this and all future instances
-            $fromdate = clone $old['start'];
+            $fromdate = clone $event['start'];
             $fromdate->setTimezone($this->server_timezone);
             $query = $this->rc->db->query(
               "DELETE FROM " . $this->db_events . "
diff --git a/plugins/calendar/drivers/kolab/kolab_calendar.php b/plugins/calendar/drivers/kolab/kolab_calendar.php
index 0f564ae3..ce6e0ec8 100644
--- a/plugins/calendar/drivers/kolab/kolab_calendar.php
+++ b/plugins/calendar/drivers/kolab/kolab_calendar.php
@@ -379,7 +379,7 @@ class kolab_calendar
         rcube::raise_error(array(
           'code' => 600, 'type' => 'php',
           'file' => __FILE__, 'line' => __LINE__,
-          'message' => "Error undeleting the event object $uid from the Kolab server"),
+          'message' => "Error undeleting the event object $event[id] from the Kolab server"),
         true, false);
     }
 
@@ -646,7 +646,7 @@ class kolab_calendar
       if (is_array($prop)) {
           foreach ($prop as $key => $val) {
               if (is_numeric($key)) {
-                  $out .= self::_complex2string($val, $fields);
+                  $out .= self::_complex2string($val);
               }
               else if (!in_array($key, $ignorekeys)) {
                 $out .= $val . ' ';