image attachment in mail with rails3

yes this will send one mail with attachment of image.png. But when i open or download that image, that is empty.?

imageurl = https://chart.googleapis.com/chart?chs=150x150&cht=qr&chl=5&choe=UTF-8

require ‘open-uri’

class UserMailer < ActionMailer::Base

default :from => “mail@example.com

def welcome_email(imageurl,mailid)

attachments[‘QR.png’] = {:mime_type => ‘image/png’,

:content => open(URI.parse(imageURL))}

mail(:to => mailid,

:subject => “Code”,

:body => “Code”)

end

end

Thanks

vishnu