Hello,

I have completed .emacs with the indications found here 
(http://emacs-fu.blogspot.com/2009/10/writing-presentations-with-org-mode-and.html), 
and I modified it :

;; Utilisation de la classe beamer
;; #+LaTeX_CLASS: beamer in org files
(unless (boundp 'org-export-latex-classes)
   (setq org-export-latex-classes nil))
(add-to-list 'org-export-latex-classes
   ;; beamer class, for presentations
   '("beamer"
      "\\documentclass[11pt,french]{beamer}\n
       \\mode<{{{beamermode}}}>\n

       \\setbeameroption{show notes}
       \\usepackage[utf8]{inputenc}\n
       \\usepackage[T1]{fontenc}\n
\\\usepackage{babel}
\\\usetheme{keynote-gradient}
\\\usepackage{beamerthemesplit}
\\\usepackage{csquotes}
       \\usepackage{hyperref}\n
       \\usepackage{color}
       \\usepackage{listings}
       \\lstset{numbers=none,language=[ISO]C++,tabsize=4,
   frame=single,
   basicstyle=\\small,
   showspaces=false,showstringspaces=false,
   showtabs=false,
   keywordstyle=\\color{blue}\\bfseries,
   commentstyle=\\color{red},
   }\n
       \\usepackage{verbatim}\n
       \\institute{{{{beamerinstitute}}}}\n
        \\subject{{{{beamersubject}}}}\n"

      ("\\section{%s}" . "\\section*{%s}")

      ("\\begin{frame}[fragile]\\frametitle{%s}"
        "\\end{frame}"
        "\\begin{frame}[fragile]\\frametitle{%s}"
        "\\end{frame}")))


The modifications concerned the French language and the use of a 
personal theme (adapted from an original model), stored in the following 
folder: home/MySelf/texmf/tex.

Here is an example of a recent work (preambule only) :
#+TITLE: title
#+DATE: today
#+AUTHOR: myself
#+STARTUP: beamer
#+LaTeX_CLASS: beamer
#+LaTeX_CLASS_OPTIONS: [bigger]
#+BEAMER_FRAME_LEVEL: 2
#+OPTIONS: toc:nil

And the frames...

When I work with Texstudio (my theme is called in this form: 
\usepackage{keynote-gradient}*), no problem: the theme is perfectly 
recognized. But not with org-mode.

Please, how can I get my theme recognized?

Thank you very much for your advice,

Frédéric

* In org-mode, \usetheme{keynote-gradient}ou 
\usepackage{keynote-gradient}have the same effects : nothing.