source block

#+BEGIN_SRC python
print "hello"
#+END_SRC

output is always

#+RESULTS:
: None

This is my org-babel configuration

    (org-babel-do-load-languages
 'org-babel-load-languages
 '((python . t)
   (C . t)
   (calc . t)
   (latex . t)
   (java . t)
   (ruby . t)
   (scheme . t)
   (sh . t)
   (sqlite . t)
   (js . t)))

Python is in PATH and executable via terminal. Emacs-lisp SRC blocks works just fine.

Any ideas?

This is my source block:

#+BEGIN_SRC python
print "hello"
#+END_SRC

The output is always:

#+RESULTS:
: None

This is my org-babel configuration:

    (org-babel-do-load-languages
 'org-babel-load-languages
 '((python . t)
   (C . t)
   (calc . t)
   (latex . t)
   (java . t)
   (ruby . t)
   (scheme . t)
   (sh . t)
   (sqlite . t)
   (js . t)))

Python is on my PATH and executable via terminal.

Emacs-lisp SRC blocks works just fine.

Why do I get None instead of hello?