Share event on groups & wall

[Folivi Fofo]

Hi,

I'm trying to post an event to facebook group by doing something like this:

    attachment = {
      "name" => @event.fb_name,
      "link" => "facebook_event_url,
      "description" => @event.description
    }

    @publication.fb_groups.each do |group|
      @api.put_wall_post(@publication.content, attachment, group.fb_id)
    end
this works fine but I only see the text, no event image, no caption.
My goal is to get the same behaviour as when you manually copy and paste a facebook event url

thx for your help