problem connecting to adroid device

[Gilles Pion]

Hello,

According to tramp's documentation
(http://www.gnu.org/software/tramp/#Android-shell-setup) I have to add the
following code in my dot emacs after having "required 'tramp":

(add-to-list 'tramp-connection-properties
    (list (regexp-quote "<my device name or IP>") "remote-shell" "sh"))

But evaluating that forms fails with the following error:
"Symbol's value as variable is void: tramp-connection-properties"

What am I doing wrong?
-- 
Gilles Pion