Error with send_file.. please help me

Ben wrote:

API is your friend.
ActionController::Streaming
send_file

I put this code block in files_controller.rb

def send_file(path, options = {}) #:doc:
raise MissingFile, “Cannot read file #{path}” unless
File.file?(path) and File.readable?(path)

    options[:length]   ||= File.size(path)
    options[:filename] ||= File.basename(path)
    send_file_headers! options

    @performed_render = false

    if options[:stream]
      render :text => Proc.new { |response, output|
        logger.info "Streaming file #{path}" unless logger.nil?
        len = options[:buffer_size] || 4096
        File.open(path, 'rb') do |file|
          if output.respond_to?(:syswrite)
            begin
              while true
                output.syswrite(file.sysread(len))
              end
            rescue EOFError
            end
          else
            while buf = file.read(len)
              output.write(buf)
            end
          end
        end
      }
    else
      logger.info "Sending file #{path}" unless logger.nil?
      File.open(path, 'rb') { |file| render :text => file.read }
    end
  end

And add this line in my page
<%= link_to ‘file download’, :action => ‘send_file(download_filename)’
%>
where download_filename is a veriable <%=
download_filename=‘/images/myfile.xls’%>

when I click the link, it display error message as
“No action responded to send_file(download_filename)”
i guess syntax error in my code, while send_file().
plz help me with the syntax as i am new.

Tuhin