The files you attached dont contain same files as your live site, so its hard to tell for sure, but I think you are just submitting your form to the wrong page.
your search form (a_search.php) is submitting the form to itself (ie the 'action' attribute of your form tag is a_search.php)
Try changing that to a_results.php, so it submits to the results page, and it should work.
<form name="form1" action="a_search.php" method="post">
<form name="form1" action="a_results.php" method="post">
Hope that helps