uploading spreadsheet to parse.com from javascript

Question

I am able to upload a spreadsheet (.csv or XLS files), but when checking on the file from Parse.com, it is all empty. I am uploading the file from client side code (not using REST). Do you think that is the problem? This works just fine for a simple image/file upload using a similar code, but fails for csv or xls type file. Here's the code:

$scope.uploadSpFile = function(fileUpload){
      var name = fileUpload.name; 
      var parseFile = new Parse.File(name, fileUpload.spFile);
      var serverUrl = 'https://api.parse.com/1/files/' + fileUpload.name;
      var mySpreadsheet = new Parse.Object(fileUpload.className);         
      $.ajax({
          type: "POST",
          beforeSend: function(request) {
            request.setRequestHeader("X-Parse-Application-Id", parse_app_id);
            request.setRequestHeader("X-Parse-REST-API-Key", parse_rest_id);
            request.setRequestHeader("Content-Type", fileUpload.spFile.type);
          },
          url: serverUrl,
          data: fileUpload.mySpreadsheet,
          processData: false,
          contentType: false,
          success: function(data) {
            mySpreadsheet.set({filetitle: data.name});
            mySpreadsheet.set({fileurl: data.url});
            mySpreadsheet.set({name: name});
            mySpreadsheet.set({fileCategory: ''});
            mySpreadsheet.set({file: {"name": data.name,"url": data.url,"__type": "File"}});
            mySpreadsheet.save();
            console.log('file saved!');
          },
          error: function(data) {
            var obj = jQuery.parseJSON(data);
            console.log('error: ' + obj.error);
            outputMsg = obj.error;
          }
        });
      }
    });

when i use a similar code to upload an image, I can access the file on my parse page, but xls or csv files turn out to be empty (actually, in XLS case, an error pops out as the format is corrupted). Anyone has any idea how to fix this issue? thanks for the help.