Adding require_once possible installation bug

main/inc/lib/skill.lib.php

@@ -17,6 +17,8 @@ define ('SKILL_TYPE_REQUIREMENT',   'required');
 define ('SKILL_TYPE_ACQUIRED',      'acquired');
 define ('SKILL_TYPE_BOTH',          'both');
 
+require_once api_get_path(LIBRARY_PATH).'model.lib.php';
+
 class SkillProfile extends Model {
     var $columns = array('id', 'name','description');
     public function __construct() {