Roo spreadsheet uploading OLE2 signature is invalid

Right so I've checked out Roo. Great gem and all and have a really basic application that doesn't have no models. And basic controller, class and view and I can't seem to get a spreadsheet to upload as I am getting `OLE2 signature is invalid` error. I have the following basic setup Controller ``` class SpreadsheetServiceController < ApplicationController def new end def create parser = SpreadsheetTagService.new(params[:spreadsheet][:file]) respond_to do |format| format.all {render :json => 'Done'} end end end ``` SpreadsheetTagService ``` class SpreadsheetTagService include Roo def initialize(uploaded_file) @tmp_destination = "#{Rails.root}/tmp/tag-import.xls" @file_path = save_file_to_tmp(uploaded_file) @file = File.new(@file_path) read_file(@file) end private def save_file_to_tmp(uploaded_file) FileUtils.mv(uploaded_file.tempfile.path, @tmp_destination ) @tmp_destination end def read_file(file) @spreadsheet = open_spreadsheet(file) @spreadsheet.each_with_pagename do |name,sheet| Rails.logger.debug( sheet ) end end def open_spreadsheet(file) case File.extname(file.path) when ".csv" then Csv.new(file.path, nil, :ignore) when ".xls" then Excel.new(file.path, nil, :ignore) when ".xlsx" then Excelx.new(file.path, nil, :ignore) else raise "Unknown file type: #{file.original_filename}" end end end ``` View ``` <%= form_tag spreadsheetupload_url, multipart: true do %> <%= file_field_tag :file %> <%= submit_tag "Import" %> <% end %> ```