Whenever I try to evaluate code I get the following:

Evaluation of this xxxxxxx code-block (xxxxx) is disabled.

Sometime I evaluated these code-blocks, I don't know what has changed since
the last time they worked.
I've tried with sh and ledger codes with the same results.

I've read the manual but I haven't found anything about it.

Org-mode version: 8.3.3
Emacs version: 24.5.1

;; Babel
(org-babel-do-load-languages
 'org-babel-load-languages
 '((R . t)
  (emacs-lisp . t)
  (gnuplot . t)
  (calc . t)
  (ditaa . t)
  (latex . t)
  (org . t)
  (sqlite . t)
  (sh . t)
  (dot . t )
  (sql . t)
  (lisp . t)
  (ledger . t)
  ))