Using Pony to send email with attachments

I have a script that I'm using to try to send an email with an attachment but for some reason I can't get both the HTML part of the email to show at the sametime as the attachment to be in the email.

Here is my code

[code] Pony.mail(         :to => to,         :from => 'Me <me@me.com>',         :subject => html_entity_decoder.decode(options[:subject]),         :html_body => "#{options[:body]}".html_safe,         :attachments => {File.basename("#{attachment}") => File.read("#{attachment}")},         :headers => { "Content-Type" => "multipart/mixed", "Content-Transfer-Encoding" => "base64", "Content-Disposition" => "attachment" },         :via => :smtp,         :via_options => {           :address => ADDRESS,           :port => '25',           :enable_starttls_auto => true,           :user_name => USERNAME,           :password => PWD,           :authentication => :plain,           :domain => DOMAIN           }       ) [/code]

I have no idea what is wrong and I have followed all of the tutorials/examples out there on google but nothing has worked