X-Cart forums - Search button not working !!!

Hello,
I wanted that my search menu should appear as separate menu under categories menu hence I modified home.tpl & search.tpl files.

It appeared correctly on home page but strangely when I click "Go" button nothing is happens but if I press enter then it's start search correctly !! 8O

What could be the problem ? :x

Here is my code for search.tpl

Code:

{* $Id: search.tpl,v 1.14 2003/08/13 06:49:07 svowl Exp $ *}

{capture name=menu}

<TABLE border=0 cellPadding=0 cellSpacing=0>

  <form method="get" action="{$xcart_web_dir}/customer/search.php" name=productsearchform>

    <tr> 

      <td width="112" height="30" rowspan="2" valign="top">{$lng.lbl_search}:</td>

      <td width="340" valign="middle"> <input type="text" name="substring" size="14" value="{$smarty.get.substring|escape}"> 

      </td>

    </tr>

    <tr> 

      <td height="22" valign="middle">

<div align="center"><a href="javascript:document.productsearchform.submit()">{include 

          file="buttons/search_head.tpl"}</a></div></td>

    </tr>

    <tr> 

      <td height="29" colspan="2" valign="top"> <div align="center"><u>{$lng.lbl_advanced_search}</u></div></td>

    </tr>

  </form>

</TABLE>

{/capture}

{ include file="menu.tpl" dingbats="dingbats_search.gif" menu_title=$lng.lbl_search menu_content=$smarty.capture.menu }