HTTP Handler context only returning null value

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C#

ASP.NET

Iam using uploadify with http handler and sending data to handler but http context alway returning null value. Please help, here is the code:

<pre lang="cs">$('#fileUpload').uploadify({
                    //'debug': true,

                    //PUBLISH MODE
                    //'swf': '/Platform/Scripts/Uploadify/uploadify.swf',
                    //'uploader': '/Platform/Scripts/Uploadify/uploadify.ashx',
                    //'cancelImg': '/Platform/Scripts/Uploadify/uploadify-cancel.png',
                    //DEBUG MODE
                    'swf': '/Scripts/Uploadify/uploadify.swf',
                    'uploader': '/Scripts/Uploadify/uploadify.ashx',
                    'cancelImg': '/Scripts/Uploadify/uploadify-cancel.png',

                    'fileTypeDesc': '*.pdf Files',
                    'fileTypeExts': '*.pdf',
                    'fileSizeLimit': '2MB',
                    'buttonText': 'Select Files',
                    'removeCompleted': false,
                    'multi': true,
                    'auto': false,
                    'data': { 'Ref': 'Test', 'Ordnum': 'NA', 'User': 'NA', 'SP': 'NA' },
                    'onUploadError': function (file, errorCode, errorMsg, errorString) {
                        alert('The file ' + file.name + ' could not be uploaded: ' + errorString);
                    },
                    'onUploadStart': function (file) {
                        var ref = $("#podref_tb").val();
                        var ordnum = $("#soNumLBL").text();
                        var user = $("#hiddenUser").val();
                        var sp = $("#hiddenSP").val();


                        $('#fileUpload').uploadify("settings", 'data', { 'Ordnum': ordnum, 'Ref': ref, 'User': user, 'SP': sp });

                    }
                });

public class uploadify : IHttpHandler
    {
        public void ProcessRequest(HttpContext context)
        {
            try
            {
                file_upload newfile = new file_upload();
                string strTest = context.Request["User"];
                newfile.user = context.Request["User"];
                newfile.sp = context.Request["SP"];

                if (newfile.user == "NA" | newfile.user == null | newfile.sp == "NA" | newfile.sp == null)
                {
                    throw new Exception("No user info");
                }

                HttpPostedFile postedFile = context.Request.Files["Filedata"];
                newfile.ordnum = context.Request["Ordnum"];
                newfile.delref = context.Request["Ref"];
                string savepath = "";
                string tempPath = "";
                tempPath = System.Configuration.ConfigurationManager.AppSettings["PODPath"];
                savepath = context.Server.MapPath(tempPath);
                string sguid = System.Guid.NewGuid().ToString();
                newfile.filename = sguid + "_" + newfile.ordnum + ".pdf";
                if (!Directory.Exists(savepath))
                {
                    throw new Exception("Problem with filepath");
                }

                postedFile.SaveAs((savepath + "\\") + newfile.filename);
                context.Response.Write((tempPath + "/") + newfile.filename);
                context.Response.StatusCode = 200;

                newfile.Save();
            }
            catch (Exception ex)
            {
                string error = "Error: " + ex.Message;
            }
        }

        public bool IsReusable
        {
            get
            {
                return false;
            }
        }
    }