same kind of elements in closest api

same kind of elements in closest api

$("ul").on("dblclick","img[src='img/arrowdown.png']",function(){
    alert($(this).closest('ul.w1m > ul').length);
});                                                                    

output is 0, but there is one "ul" in other "ul.w1m"
why output is not 1?

<
ul  class = "w1m" >
<li><div><img src="img/minus.png"><img src="img/arrowdown.png"><img src="img/link.png"></div><div id="wu1m2" contenteditable="true" class="w1mc">b</div>
</li>
      <ul>
           <li><div><img src="img/minussub.png"><img src="img/link.png"></div><div id="wu1s0m2" class="w1smc" contenteditable="true">Websites</div>
 </li>
         <li><div><img src="img/minussub.png"><img src="img/link.png"></div><div id="wu1s1m2" class="w1smc" >Illustrations</div>
 </li>

< li > < div > < img  src = "img/minussub.png" > < img  src = "img/link.png" > </ div > < div  id = "wu1s2m2"  class = "w1smc"  > Photography </ div >
</li>
    </ul>
</ul>