Hi, I'm trying to generate some figure with R, into an org session. Firstly
I use the code in the org site. The problem is that the code do not
generate any figure.

This is the code:

#+TITLE:Test
#+AUTHOR: Your Name
#+EMAIL: your-email@server.com
#+BABEL: :session *R* :cache yes :results output graphics :exports
both :tangle yes

* Example of Org-Babel for R Literate Programming
** R text output
A simple summary.
#+begin_src R
  x <- rnorm(10)
  summary(x)
#+end_src

** R graphics output
Note we use the object =x= generated in previous code block, thanks to
the header option =:session *R*=.  The output graphics file is
=a.png=.

#+begin_src R  :file a.png
  y <- rnorm(10)
  plot(x, y)
#+end_src

Same plot with larger dimension:

#+begin_src R  :file b.png :width 800 :height 800
  plot(x, y)
#+end_src


Where do I wrong?

Best
Riccardo