#channel_id.message_post(body=body,
#subject=title,
#subtype_xmlid='mail.box_inbox',
#author_id=self.env.user.partner_id.id,
#attachment_ids=[attachment.id],)

from this code i am sending the ir.attachment(514,) object . but the message is a  blank image or blank pdf .

 
am i missing something?