>>> "Eric" == Eric S Fraga <esflists@gmail.com> writes:

   > Can you be explicit about how you are exporting to beamer 

Either 

C-c C-e l l

Or 

C-c C-e l o

   > and what version of org you are using? 

The latest master version 
commit adec504d5ba3f2089cb689ce5a59692a8ebf6735
   > What happens if you start emacs with -Q?

Then both commands do work (even I do not need 'ox-beamer)

So the problem is in my init file and I am quite sure that it has to do
with the following lines in my custom- file

 '(org-latex-classes
   '(("article" "\\documentclass[12pt]{article}"
      ("\\section{%s}" . "\\section*{%s}")
      ("\\subsection{%s}" . "\\subsection*{%s}")
      ("\\subsubsection{%s}" . "\\subsubsection*{%s}")
      ("\\paragraph{%s}" . "\\paragraph*{%s}")
      ("\\subparagraph{%s}" . "\\subparagraph*{%s}"))
     ("report" "\\documentclass[12pt]{report}"
      ("\\part{%s}" . "\\part*{%s}")
      ("\\chapter{%s}" . "\\chapter*{%s}")
      ("\\section{%s}" . "\\section*{%s}")
      ("\\subsection{%s}" . "\\subsection*{%s}")
      ("\\subsubsection{%s}" . "\\subsubsection*{%s}"))
     ("book" "\\documentclass[12pt]{book}"
      ("\\part{%s}" . "\\part*{%s}")
      ("\\chapter{%s}" . "\\chapter*{%s}")
      ("\\section{%s}" . "\\section*{%s}")
      ("\\subsection{%s}" . "\\subsection*{%s}")
      ("\\subsubsection{%s}" . "\\subsubsection*{%s}"))
     ("exam" "\\documentclass[12pt, addpoints, answers]{exam}"
      ("\\begin{questions}%%%s" "\\end{questions}" "\\begin{questions}%%%s" "\\end{questions}")
      ("\\titledquestion{%s}" . "")
      ("\\begin{parts}%%%s" "\\end{parts}" "\\begin{parts}%%%s" "\\end{parts}")
      ("\\part[%s] " . "")
      ("\\begin{subparts}%%%s" "\\end{subparts}" "\\begin{subparts}%%%s" "\\end{subparts}")
      ("\\subpart[%s] " . "")
      ("\\begin{solution}[%s]" "\\end{solution}" "\\begin{solution}[%s]"
   "\\end{solution}"))))

I have them because I wanted to add the latex exam class and that is
what custom is for. For some bizarre reason 

The code 
(unless (assoc "beamer" org-latex-classes)
  (add-to-list 'org-latex-classes
	       '("beamer"
		 "\\documentclass[presentation]{beamer}"
		 ("\\section{%s}" . "\\section*{%s}")
		 ("\\subsection{%s}" . "\\subsection*{%s}")
		 ("\\subsubsection{%s}" . "\\subsubsection*{%s}"))))

In ox-beamer

Is ignored. It looks like a bug to me.