I am very sorry and I apologize for my useless email.
A first correct reply to my problem was given four days ago on this list:
(Now I meet "overfullbox messages" and pdf is not produced... but that it is another question.)
---------- Forwarded message ----------
From:
Josiah Schwab <address@hidden>Date: 2016-02-22 19:52 GMT+01:00
Subject: Re: [O] ox-beamer export, no frames created
To: "John W. Burroughs" <
address@hidden>
Cc:
address@hiddenHello John,
> I have been trying to produce my first presentation using org-mode and
> ox-beamer export to create a pdf. I am not seeing separate frames for
> each slide. For example, using the Beamer Example (12.5.6) from the
> org-mode manual, I get the following generated .tex file.
>
> There are only \subsection{} generated, instead of the \begin{frame}
> that is expected.
To me, this looks like you used the LaTeX export commands instead of the
beamer export commands.
http://orgmode.org/manual/Beamer-export-commands.html#Beamer-export-commands
Best,
Josiah