My Html Markup is like this

<div id="main">
    <div id="slider">
        <img src=""/>
    </div> 
    <div class="clear slider"></div>

    <div class="slider ndslider">
        <a href="#" rel="bookmark">
            <img src="#" title=""/>
        </a>
    </div>    

    <div class="slider rdslider">
        <a href="" rel="bookmark">
            <img src="" title=""/>
        </a>
   </div>       
<div class="slider thslider nivoSlider">
    <a rel="bookmark" href="" class="nivo-imageLink" >
        <img src="image src" >
    </a>
    <a rel="bookmark" href="" class="nivo-imageLink">
        <img title="" src="">
    </a>
    <a rel="bookmark" href="#" class="nivo-imageLink">
        <img title="" src="">
    </a>
    <div class="nivo-slice"></div>
    <div class="nivo-slice"></div>
    <div class="nivo-slice"></div>
    <div class="nivo-directionNav">
        <a class="nivo-prevNav">Prev</a>
        <a class="nivo-nextNav">Next</a>
   </div>
   <div class="nivo-controlNav">
        <a rel="0" class="nivo-control active">
            <img alt="" src="undefined">
        </a>
        <a rel="1" class="nivo-control">
            <img alt="" src="undefined">
       </a>
   </div>
</div>
</div>

I want to find the all the images inside this DIV

<div class="slider thslider nivoSlider">

</div>

and set that images on to this

<div class="nivo-controlNav">
      <a rel="0" class="nivo-control active">
          <img alt="" src="undefined">
      </a>
</div>

For Doing the same i had written my custom jQuery but it is not working.

jQuery(document).ready(function() {
     jQuery('.thslider a img').each(function(){
            var imgSrc = jQuery(this).attr('src');
            var newSrc = 'http://saorabh-test1.rtcamp.info/wp-content/themes/twentyten/timthumb.php?src='+ imgSrc +' &h=50&w=50&zc=1';
            jQuery(".thslider .nivo-controlNav a img").attr('src',newSrc);

        });
    });

Help me..