SWFUpload able to load the browsing window when clicked but unable to reach the upload page

Question

Hello I have a problem of using swfupload to upload the image to the aspx page. I can open the browsing window to select the file to upload but unable to reach to upload page.

This is my javascript code that initializing the swfupload

var swfu;

   window.onload = function() {
   var settings = 
            {
           file_size_limit: "1000", // 200 kb
           file_types: "*.jpg;*.gif;*.png",
           file_types_description: "Image Files",
           file_upload_limit: "10",
           file_queue_limit: "10",


           upload_url: "/Membership/ExportFromFlash.aspx?action=gadget",
           flash_url: "/Html_Data/Flash/swfupload.swf",
           post_params: {
               "ASPSESSID": "<%=Session.SessionID %>"
           },
           debug : false,
           button_width: "100",
           button_height: "20",
           button_placeholder_id: "swfuploadContainer",
           button_text: '<span>Upload your gadgets</span>',
           button_text_style: ".theFont { font-size: 8; }",
           button_text_left_padding: 12,

           upload_error_handler: uploadError,
           upload_success_handler : uploadSuccess
           }
           swfu = new SWFUpload(settings);

       };

       function uploadError(file, errorCode, message) {
           try {
               alert(message);
           } catch (ex) {
               alert("ASDF");
               this.debug(ex);
           } 
       }
       function uploadSuccess(file, serverData) {
           try {
               alert(serverData);
               //window.navigator("/Membership/GadgetDetails.aspx");
           } catch (ex) {
               alert("A33");
               this.debug(ex);
           }
       }