diff --git a/main/gradebook/gradebook_edit_link.php b/main/gradebook/gradebook_edit_link.php
index b6fc523c4c..9d455eacfd 100755
--- a/main/gradebook/gradebook_edit_link.php
+++ b/main/gradebook/gradebook_edit_link.php
@@ -15,9 +15,10 @@ $course_id              = GradebookUtils::get_course_id_by_link_id($_GET['editli
 $tbl_forum_thread 		= Database :: get_course_table(TABLE_FORUM_THREAD);
 $tbl_work 				= Database :: get_course_table(TABLE_STUDENT_PUBLICATION);
 $tbl_attendance 		= Database :: get_course_table(TABLE_ATTENDANCE);
+
 $linkarray 				= LinkFactory :: load($_GET['editlink']);
+/** @var AbstractLink $link */
 $link = $linkarray[0];
-
 if ($link->is_locked() && !api_is_platform_admin()) {
     api_not_allowed();
 }
@@ -51,7 +52,7 @@ if ($form->validate()) {
     if (!empty($values['select_gradebook'])) {
         $link->set_category_id($values['select_gradebook']);
     }
-    $link->set_visible(empty ($values['visible']) ? 0 : 1);
+    $link->set_visible(empty($values['visible']) ? 0 : 1);
     $link->save();
 
     //Update weight for attendance
diff --git a/main/gradebook/lib/be/forumthreadlink.class.php b/main/gradebook/lib/be/forumthreadlink.class.php
index 1aa98a3b4a..ae60cb02a1 100755
--- a/main/gradebook/lib/be/forumthreadlink.class.php
+++ b/main/gradebook/lib/be/forumthreadlink.class.php
@@ -95,15 +95,15 @@ class ForumThreadLink extends AbstractLink
 		}
 
 		$sql = 'SELECT tl.thread_id, tl.thread_title, tl.thread_title_qualify
-				FROM '.$tbl_grade_links.' tl ,'.$tbl_item_property.' ip
+				FROM '.$tbl_grade_links.' tl INNER JOIN '.$tbl_item_property.' ip
+				ON (tl.thread_id = ip.ref AND tl.c_id = ip.c_id )
 				WHERE
 				    tl.c_id = '.$this->course_id.' AND
                     ip.c_id = '.$this->course_id.' AND
-                    tl.thread_id = ip.ref AND
                     ip.tool = "forum_thread" AND
                     ip.visibility<>2 AND
                     '.$session_condition.'
-                GROUP BY ip.ref ';
+                ';
 
 		$result = Database::query($sql);
 
@@ -357,7 +357,10 @@ class ForumThreadLink extends AbstractLink
 		$ref_id = $this->get_ref_id();
 		if (!empty($ref_id)) {
 			//Cleans forum
-			$sql = 'UPDATE '.$this->get_forum_thread_table().' SET thread_qualify_max=0,thread_weight=0,thread_title_qualify=""
+			$sql = 'UPDATE '.$this->get_forum_thread_table().' SET
+			        thread_qualify_max = 0,
+			        thread_weight = 0,
+			        thread_title_qualify = ""
                     WHERE c_id = '.$this->course_id.' AND thread_id= '.$ref_id;
 			Database::query($sql);
 		}
diff --git a/main/work/work.lib.php b/main/work/work.lib.php
index 568c760ebd..3ae6dedd95 100755
--- a/main/work/work.lib.php
+++ b/main/work/work.lib.php
@@ -1593,7 +1593,7 @@ function getWorkListTeacher(
             }
             // Remove Delete Work Button from action List
             // Because removeXSS "removes" the onClick JS Event to do the action (See model.ajax.php - Line 1639)
-            // But still can use the another jqgrid button to remove works (trash icon) 
+            // But still can use the another jqgrid button to remove works (trash icon)
             //
             // $deleteUrl = api_get_path(WEB_CODE_PATH).'work/work.php?id='.$workId.'&action=delete_dir&'.api_get_cidreq();
             // $deleteLink = '<a href="#" onclick="showConfirmationPopup(this, \'' . $deleteUrl . '\' ) " >' .
@@ -3783,14 +3783,16 @@ function addDir($formValues, $user_id, $courseInfo, $group_id, $session_id)
             'filetype' => 'folder',
             'post_group_id' => $group_id,
             'sent_date' => $today,
-            'qualification' => $formValues['qualification'] != '' ? $formValues['qualification'] : '',
-            'parent_id' => '',
-            'qualificator_id' => '',
-            'weight' => $formValues['weight'],
+            'qualification' => $formValues['qualification'] != '' ? $formValues['qualification'] : 0,
+            'parent_id' => 0,
+            'qualificator_id' => 0,
+            'weight' => !empty($formValues['weight']) ? $formValues['weight'] : 0,
             'session_id' => $session_id,
             'allow_text_assignment' => $formValues['allow_text_assignment'],
             'contains_file' => 0,
             'user_id' => $user_id,
+            'has_properties' => 0,
+            'document_id' => 0
         ];
         $id = Database::insert($work_table, $params);