Dear Yves,
Yes, after deleting that line, it worked fine.
But, it is my fault even though the file is from you.
If I know better and more careful to check, then it would not be
happened.
> \setcounter{secnumdepth}{5}
Thank you for your comment also.
I learned a lot from the people in this list.
Tahnks all.
Best regards,
Dalyoung