Configure Wifi (hidden SSID) on Raspbian (EDIMAX Wifi Adapter) - configuration

Question

I have trouble connecting to the wifi network with my Raspberry Pi (Raspbian Wheezy) in combination with EDIMAX EW-7811UN Wireless USB Adapter.
I already used this combination to connect to my parents wifi (WPA with a non-hidden wifi) successfully.
/etc/network/interfaces
auto lo
iface lo inet loopback
iface eth0 inet static
address 192.168.2.128
netmask 255.255.255.0
gateway 192.168.2.1
auto wlan0
allow-hotplug wlan0
iface wlan0 inet static
address 192.168.2.128
netmask 255.255.255.0
gateway 192.168.2.1
wpa-ap-scan 1
wpa-ap-ssid 1
wpa-ssid "<SSID>"
wpa-psk "<PASS>"
My own wifi has the following configuration:
hidden SSID
TKIP+AES (WPA/WPA2) with PSK authentication
So I generated a PSK version of my wifi password:
$ wpa_passphrase "<SSID>" "<PASS>"
And configured these two files:
/etc/network/interfaces
auto lo
iface lo inet loopback
iface eth0 inet dhcp
auto wlan0
allow-hotplug wlan0
iface wlan0 inet dhcp
wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf
iface default inet dhcp
and /etc/wpa_supplicant/wpa_supplicant.conf
ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
network={
ssid="<SSID"
psk=<PSK>
proto=WPA2
key_mgmt=WPA_PSK
pairwise=CCMP
group=CCMP
auth_alg=OPEN
}
The USB Adapter and its module are working fine (lsusb, lsmod). And as I said, I already used the Raspberry Pi to connect to a network. But it does not seem work with the configuration I use at my own home. I get an "Network unreachable" error if I try to ping my router.
Resetting the Raspberry Pi is not an option, because I already put a lot of effort in its configuration.
Does anybody have a simular configuration with his own Raspberry Pi or knows how to solve this (I already googled and tried different "solutions" for hours without any success).
Thank you,
Freddi

Answer 1

I finally found my answer here (sorry, it is german): Raspberry Pi, Edimax EW-7811Un and a hidden wifi
# /etc/network/interfaces
allow-hotplug wlan0
auto wlan0
iface wlan0 inet dhcp
wpa-ap-scan 1
wpa-scan-ssid 1
wpa-ssid "SSID"
wpa-proto RSN
wpa-pairwise CCMP
wpa-key-mgmt WPA-PSK
wpa-psk "PASS"

Answer 2

I think you forgot in the first aproach adding
scan_ssid=1
to the network block in wpa_supplicant.conf to make the network work with hidden ssid.
From the docs:
scan_ssid
SSID scan technique; 0 (default) or 1. Technique 0 scans for the
SSID using a broadcast Probe Request frame while 1 uses a
directed Probe Request frame. Access points that cloak them-
selves by not broadcasting their SSID require technique 1, but
beware that this scheme can cause scanning to take longer to com-
plete.