diff --git a/infolog/inc/class.infolog_so.inc.php b/infolog/inc/class.infolog_so.inc.php
index f637116524..6291d2017f 100644
--- a/infolog/inc/class.infolog_so.inc.php
+++ b/infolog/inc/class.infolog_so.inc.php
@@ -902,6 +902,15 @@ class infolog_so
 		// do not return deleted attendees
 		$join .= " LEFT JOIN $this->users_table attendees ON main.info_id=attendees.info_id AND attendees.info_res_deleted IS NULL";
 		$group_by = ' GROUP BY main.info_id ';
+		// check if $query['append'] already contains a GROUP BY clause
+		if (stripos($query['append'], 'group by') !== false)
+		{
+			$query['append'] .= ',main.info_id ';
+		}
+		else
+		{
+			$query['append'] = $group_by;
+		}
 		$pid = 'AND ' . $this->db->expression($this->info_table,array('info_id_parent' => ($action == 'sp' ?$query['action_id'] : 0)));
 
 		if ($GLOBALS['egw_info']['user']['preferences']['infolog']['listNoSubs'] != '1' && $action != 'sp' ||
@@ -952,7 +961,7 @@ class infolog_so
 				if (is_array($cols)) $cols = implode(',',$cols);
 				$cols .= ','.$this->db->group_concat('attendees.account_id').' AS info_responsible';
 				$rs = $this->db->query($sql='SELECT '.$mysql_calc_rows.' '.$distinct.' '.$cols.' '.$info_customfield.' '.$sql_query.
-					$query['append'].$group_by.' '.$ordermethod,__LINE__,__FILE__,
+					$query['append'].$ordermethod,__LINE__,__FILE__,
 					(int) $query['start'],isset($query['start']) ? (int) $query['num_rows'] : -1,false,Api\Db::FETCH_ASSOC);
 				//echo "<p>db::query('$sql',,,".(int)$query['start'].','.(isset($query['start']) ? (int) $query['num_rows'] : -1).")</p>\n";