diff --git a/htdocs/mrp/class/mo.class.php b/htdocs/mrp/class/mo.class.php
index 274782a14ea..17d4217bbcd 100644
--- a/htdocs/mrp/class/mo.class.php
+++ b/htdocs/mrp/class/mo.class.php
@@ -106,7 +106,7 @@ class Mo extends CommonObject
 		'note_public' => array('type'=>'html', 'label'=>'NotePublic', 'enabled'=>1, 'visible'=>0, 'position'=>61, 'notnull'=>-1,),
 		'note_private' => array('type'=>'html', 'label'=>'NotePrivate', 'enabled'=>1, 'visible'=>0, 'position'=>62, 'notnull'=>-1,),
 		'date_creation' => array('type'=>'datetime', 'label'=>'DateCreation', 'enabled'=>1, 'visible'=>-2, 'position'=>500, 'notnull'=>1,),
-		'tms' => array('type'=>'timestamp', 'label'=>'DateModification', 'enabled'=>1, 'visible'=>-2, 'position'=>501, 'notnull'=>-1,),
+		'tms' => array('type'=>'timestamp', 'label'=>'DateModification', 'enabled'=>1, 'visible'=>-2, 'position'=>501, 'notnull'=>1,),
 		'date_valid' => array('type'=>'datetime', 'label'=>'DateValidation', 'enabled'=>1, 'visible'=>-2, 'position'=>502,),
 		'fk_user_creat' => array('type'=>'integer', 'label'=>'UserAuthor', 'enabled'=>1, 'visible'=>-2, 'position'=>510, 'notnull'=>1, 'foreignkey'=>'user.rowid',),
 		'fk_user_modif' => array('type'=>'integer', 'label'=>'UserModif', 'enabled'=>1, 'visible'=>-2, 'position'=>511, 'notnull'=>-1,),