Little problem with parallax

i use for stage (this is responsive)
width : with %

heigth : with px

i have in my compositionReady some fixebale element like that

$("body").append($("#Stage_element").css("position", "fixed"));

and function for parallax :

yepnope({

    load: "http://cdn.edgecommons.org/an/1.0.0/js/min/EdgeCommons.js",

          callback: function() {

                    EC.centerStage(sym);

                    EC.Parallax.setup(sym);

          }

});

the probleme is :

if i insert a picture and make it responve i build an animation for here she start lately and i can't see the animation to the end  !!!!!

some ine answer me please