[jQuery] slidedown menu

[dima_mak]

I am trying to do an slidedown menu with hover function:
Javascript:
Code:

$(document).ready(function(){

    $("#rightmenu ul li").hover(
      function () {
            $(this).find("ul:first").stop(true, true);
            $(this).find("ul:first").slideDown();
      },
      function () {
            $(this).find("ul:first").slideUp('fast');
      }
    );
  });

HTML:
Code:

      <div id="rightmenu">
         <ul id="ulmenu">
            <li>
               <a href="#">סנן לפי סגנון</a>
               <ul>
<li>1</li>
<li>2</li>
<li>3</li>
               </ul>
            </li>
</ul></div>

It works fine in IE, but not in FF(it doesn't shown at all)
Here is example - www.rollshop.co.il