Impossible d'exécuter la requête

DEBUG MODE

SQL Error : 1054 Unknown column '_NAV_VIDEO' in 'where clause'

SELECT n.id__nav, tr._nav, n.url_page FROM _nav n INNER JOIN trad__nav tr on n.id__nav = tr.id___nav WHERE id__nav_pere = _NAV_VIDEO AND n.id__type_nav = 1 AND selected = 1 AND tr.id__langue = 1 ORDER BY ordre

Line : 25
File : /home/risoul18/www/include/lib_navigation.inc.php