downloads failing in ruby 1.8.7

I am including a pdf file card for download.

1. I add card and specified the file type and I select the file to upload to the server.

2. THe file is uploaded and I can see it on ther server.

3. However when I select the card it tries to upload it but I get a wagn Hitch. 

4.  I am ruby 1.8.7

5. I copied the exception stack below.

6. CODE I added ... Exception is in render_show_file

7.  the error was in render_show_file in the application_controller. I put some print statements.

The params were empty. It is indeed null

  def render_show_file
    return fast_404 if !@card
    @card.selected_rev_id = (@rev_id || @card.current_revision_id).to_i
 
    format = @card.attachment_format(params[:format])
    return fast_404 if !format

    if ![format, 'file'].member?( params[:format] )
      return redirect_to( request.fullpath.sub( /\.#{params[:format]}\b/, '.' + format ) ) #@card.attach.url(style) )
    end

    style = @card.attachment_style( @card.typecode, params[:size] || @style )
    return fast_404 if !style
    fileHandle = File.open("/tmp/mikesLog", "w")
    fileHandle.puts "HELLO GOT TO HERE"
    fileHandle.puts style
    fileHandle.puts @card.inspect
    fileHandle.close
    send_file @card.attach.path(style),
      :type => @card.attach_content_type,
      :filename =>  "#{@card.cardname.to_url_key}#{style.blank? ? '' : '-'}#{style}.#{format}",
      :x_sendfile => true,
      :disposition => (params[:format]=='file' ? 'attachment' : 'inline' )
  end