请教,出现如题所示问题,Notice: Trying to get property of non-object in ..
不知道怎么处理.

前后几行代码:

CONCAT_WS('/',folder,element) AS lookup"
  . "\nFROM #__mambots"
  . "\nWHERE published >= 1 AND access <= $my->gid AND folder='$group'"
  . "\nORDER BY ordering"
  );

请指点: 谢谢！！！！！

曼波什么版本，在哪里操作出现此 notice，notice所在行数是多少？