You have an ancient version of Zen Cart, about five years old, and the files are quite different from the current version. This one does do much the same things as the current version of it, and it does have the file call that should produce the product listing:
require($template->get_template_dir('tpl_list_box_content.php',DIR_WS_TEMPLATE, $current_page_base,'common'). '/tpl_list_box_content.php');
That file exists or there would be a fatal error.
I could dig further, but the first thing you need to do to keep from getting hacked is upgrade to the latest version of Zen Cart. This will require redoing your template, as the template system switched from table-based to CSS shortly after your version. It also may resolve your problem, as the current files are built to work correctly.
You say "This site is upgraded from 1.2 to 1.3.9", but the files and output I can see are still the old versions.
Did you merge or update the /cornelis/ template files? If not, that would explain your trouble.