Hi bsalimi
I don't have an available network to use the configuration that you need. But I found this other link to initialize the wpa_supplicant. But I'm not sure about the interface that is used for that case.
Your configurations seems to be fine, but make sure that you are booting with the SDcard, and change the path (in /etc/network/interfaces ) of:
wpa-conf /etc/wpa_supplicant.conf
to
wpa-conf /var/volatile/run/wpa_supplicant.conf
The path of your wpa_supplicant.conf file.
If still doesn't work try to add the configuration under the wpa-driver wext in /etc/network/interfaces and erase the wpa-conf /etc/wpa_supplicant.conf line
Let me know it this works, I will try to search for someone using this configuration.
Regards;
CMata