In fact, when I type date in my terminal, I always get the following date :
Tue Sep 9 12:31:36 CEST 2014
Only time is changing.
If I let my RPi turned on, of course, the date will change but when I turn it off and restart it, the date is still Tue Sep 9 xx:xx:xx CEST 2014
Of course, I used dpkg-reconfigure tzdata
and selected the good geographic area and time zone. But nothing changed.