diff --git a/db/install.php b/db/install.php
index 0433ec9..5cc1af6 100644
--- a/db/install.php
+++ b/db/install.php
@@ -34,7 +34,7 @@ function xmldb_attforblock_install() {
 	$result = true;
 	$arr = array('P' => 2, 'A' => 0, 'L' => 1, 'E' => 1);
 	foreach ($arr as $k => $v) {
-		unset($rec);
+		$rec = new stdClass;
 		$rec->attendanceid = 0;
 		$rec->acronym = get_string($k.'acronym', 'attforblock');
 		$rec->description = get_string($k.'full', 'attforblock');
diff --git a/export.php b/export.php
index c5916e0..0d47952 100644
--- a/export.php
+++ b/export.php
@@ -77,6 +77,7 @@ if ($mform->is_submitted()) {
         $filename = clean_filename($course->shortname.'_Attendances_'.userdate(time(), '%Y%m%d-%H%M'));
 
 		$group = $formdata->group ? $reportdata->groups[$formdata->group] : 0;
+        $data = new stdClass;
         $data->tabhead = array();
         $data->course = $att->course->fullname;
         $data->group = $group ? $group->name : get_string('allparticipants');
diff --git a/locallib.php b/locallib.php
index 346e569..68633de 100644
--- a/locallib.php
+++ b/locallib.php
@@ -1292,12 +1292,14 @@ function att_update_all_users_grades($attid, $course, $context) {
     $statuses = att_get_statuses($attid);
     $gradebook_maxgrade = att_get_gradebook_maxgrade($attid);
     foreach ($userids as $userid) {
-        $grades[$userid]->userid = $userid;
+        $grade = new stdClass;
+        $grade->userid = $userid;
         $userstatusesstat = att_get_user_statuses_stat($attid, $course->startdate, $userid);
         $usertakensesscount = att_get_user_taken_sessions_count($attid, $course->startdate, $userid);
         $usergrade = att_get_user_grade($userstatusesstat, $statuses);
         $usermaxgrade = att_get_user_max_grade($usertakensesscount, $statuses);
-        $grades[$userid]->rawgrade = att_calc_user_grade_fraction($usergrade, $usermaxgrade) * $gradebook_maxgrade;
+        $grade->rawgrade = att_calc_user_grade_fraction($usergrade, $usermaxgrade) * $gradebook_maxgrade;
+        $grades[$userid] = $grade;
     }
 
     return grade_update('mod/attforblock', $course->id, 'mod', 'attforblock',
diff --git a/preferences.php b/preferences.php
index c09ed2e..24ef61d 100644
--- a/preferences.php
+++ b/preferences.php
@@ -85,9 +85,9 @@ switch ($att->pageparams->action) {
         $att->update_status($att->pageparams->statusid, null, null, null, 1);
         break;
     case att_preferences_page_params::ACTION_SAVE:
-        $acronym 		= required_param('acronym', PARAM_MULTILANG);
-        $description	= required_param('description', PARAM_MULTILANG);
-        $grade			= required_param('grade', PARAM_INT);
+        $acronym 		= required_param_array('acronym', PARAM_MULTILANG);
+        $description	= required_param_array('description', PARAM_MULTILANG);
+        $grade			= required_param_array('grade', PARAM_INT);
 
         foreach ($acronym as $id => $v) {
             $att->update_status($id, $acronym[$id], $description[$id], $grade[$id], null);