Latex export does not include inlined files

Question

I have a org file (paper.org) which includes inlined files (abstract.org,intro.org). Like this,

** Introduction
#+INCLUDE: intro.org
** Results
#+INCLUDE: results.org

When I export to a pdf (C-c C-e d), The subsections in the intro.org do not appear in the generated pdf. Do I need to set a variable? The included files appear when I export to html.

EDIT

As requested, here is a MWE.

== paper.org ==

• Abstract
  #+INCLUDE: "abs.org"
• Intro
  #+INCLUDE: "intro.org"

== abs.org ==

This is the abstract. This should appear.
** Abstract Subsection
This will not.

== intro.org ==

This is intro. This will appear in the pdf.
** Subsection in Intro
But this will not.

Answer 1

This was a problem with the version of org-mode that I was using. This and another problem were solved when I upgraded. See link.

Answer 2

There is an example of what you want to do in the manual, at http://orgmode.org/manual/Include-files.html#Include-files.

If that does not work, provide us with a MWE and/or write to the ML -- that could be a bug, then.