Troubles with custom agenda commands

["Sebastien Vauban" <wxhgmqzgwmuf-geNee64TY+gS+FvcfC7Uqw@public.gmane.org>]

Hello,

Trying to write my own custom agenda commands, I face a couple of weird
behaviors.

#+begin_src emacs-lisp
  (add-to-list 'org-agenda-custom-commands
               '("S" "Summary Review"
                 ((agenda "")
                  (todo ""))
                 ((org-agenda-time-grid nil)
                  (org-agenda-clockreport-mode nil)
                  (org-deadline-warning-days 0))))
#+end_src

Having the above (which is correct, AFAICT from following the tutorial on
http://orgmode.org/worg/org-tutorials/org-custom-agenda-commands.html):

1. When getting to the agenda dispatcher (`C-c a'), I see:

--8<---------------cut here---------------start------------->8---
   S   Summary Review: set of 3 commands
--8<---------------cut here---------------end--------------->8---

  while I only have... 2 commands (`agenda' and `todo'). Why?

2. When firing it up (`C-c a' followed by `S'), I get the 2 blocks I was
   expecting, but also an error:

--8<---------------cut here---------------start------------->8---
   Buffer is read-only: #<buffer *Org Agenda(S)*>
--8<---------------cut here---------------end--------------->8---

Can you confirm this?

Best regards,
  Seb

-- 
Sebastien Vauban