Getting source code to work

[Mark Stoehr <stoehr@cs.uchicago.edu>]

Hi,  I'm trying to include python source code in my document and I'm
finding that org-babel-execute-buffer ( as well as C-c C-c at the end
of a code block) does not successfully run my code, instead I get an
error "Invalid function: org-save-outline-visibility".  I saw messages
earlier

http://thread.gmane.org/gmane.emacs.orgmode/28048/focus=28049

regarding an apparently similar problem but my understanding of emacs
lisp is insufficient for me to make sense of it.  My program:

#+BEGIN_SRC python
print "Hello World"
return 1+2
#+END_SRC


I also have trouble getting tangle to work. With the following problem


#+BEGIN_SRC python :tangle yes
print "Hello World"
return 1+2
#+END_SRC

both C-c C-v t and M-x org-babel-tangle fail saying that 0 blocks have
been tangled.  I also tried the examples with the #+BEGIN_SRC and
#+END_SRC being in lowercase and that didn't change anything.