[AUCTeX] installing elpa AucTeX, obtaining: "Symbol's function definition is void: TeX-add-to-alist" error

[TeXnicien de Surface]

hello all

Since today I've used an 'old' version of AucTeX installed from tarball
and it worked almost fine.

Since I'm in a period where I can take some time to better my ubuntu box
I've decided to upgrade with elpa.

On
GNU Emacs 24.3.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.4.2)
of 2013-09-03 on novatux-laptop

I've put this in my .emacs:

<.emacs>
(add-to-list 'load-path
             (expand-file-name
                "/home/novatux/.emacs.d/elpa/auctex-11.87.5/"))

(load "auctex.el" nil t t)

;; Make AUCTeX aware of style files and multi-file documents
(setq TeX-parse-self t) ; Enable parse on load.
(setq TeX-auto-save t) ; Enable parse on save.
(setq-default TeX-master nil) ; demande le maitre

</.emacs>

Now for the strange behaviour:

when I try to open a tex file (with C-x C-f)
I get the message:
Symbol's function definition is void: TeX-add-to-alist

The file is nonetheless opened, I see it in the list of buffers.
I can go to the buffer and then auctex seems to work fine.

But this is quite an annoying behaviour.

What could I do to make things right?

Any hint will be greatly appreciated.

Many thanks in advance


-- 
Le TeXnicien de Surface