ActionMailer Problem

Hi, I wanted to send an attachment in mail. for testing , I have send png image attachement in mail. Mail delivery is completely working but the attachment in that mail show file name as “nonname” what should i do?? My code is:

class SendMail < ActionMailer::Base default :from => “

def welcome attachments[“adfd.txt”] =“#{Rails.root}/public/images/f.txt”)

 mail(:to => "",
      :subject => "welcome mail").deliver