使用ajax后，lazyload.js失效怎么办

$('body').on('mouseover' , '.myDrop' ,
        function() {
          $(this).addClass('open');
        }
    );

$(function() {
    $("img.img-responsive").lazyload({
      effect : "fadeIn",
      threshold : 200
    });
  });

$.ajax({
   type: "POST",
   url: "XXX",
   data: "XXXX",
   success: function(msg){
     $("img.img-responsive").lazyload({
      effect : "fadeIn",
      threshold : 200
    });
   }
});