Rails 3 + fb_graph how to get access token to post to my own Facebook page

I am using Rails 3 + fb_graph to post to my own Facebook page. I have
code that works, but it uses an access token that only works for a
couple of hours. And it is very annoying to refresh this access token a
couple of times a day. So I registrated for a FB app. I now have:

  my_app = FbGraph::Application.new("App ID");
  acc_tok = my_app.get_access_token("App Secret");
  me = FbGraph::User.me(acc_tok)
  me.fetch
  me.accounts
  account = me.accounts.select {|account| account if account.name ==
"BoaJobs.com"}.first

  page = FbGraph::Page.new(account.identifier)

  note = page.note!(:access_token => account.access_token, :subject =>
@title, :message => @message, :link => @url)

But I am getting an error on the me.fetch line:

  OAuthException :: An active access token must be used to query
information about the current user.

Can somebody post some code that helps me solve this problem. Thank you
very much in advance.