can't convert Fixnum into String (TypeError)

(TDiary::Plugin#eval_src):112:in `concat'
/usr/local/httpd/htdocs/mini/diary/tdiary.rb:75:in `join'
/usr/local/httpd/htdocs/mini/diary/tdiary.rb:75:in `safe'
/usr/local/httpd/htdocs/mini/diary/tdiary.rb:657:in `eval_src'
/usr/local/httpd/htdocs/mini/diary/tdiary.rb:904:in `do_eval_rhtml'
/usr/local/httpd/htdocs/mini/diary/tdiary.rb:854:in `eval_rhtml'
/usr/local/httpd/htdocs/mini/diary/index.rb:71