May be you are making some configuration with Realtek 8188EUS wireless adapter on Gentoo Linux, and everything looks well except "wpa_supplicant". Thanks to "The Linux Rain", here is the right command connecting to the network. But if you want to start wireless network during system booting, just insert several words to file "/etc/init.d/wpa_supplicant", and get "/etc/init.d/wicd" started long before "/etc/init.d/wpa_supplicant". File content before edit (line 8) :

command_args="$wpa_supplicant_args -B -c$wpa_supplicant_conf $wpa_supplicant_if"

After edit:

command_args="$wpa_supplicant_args -B -Dwext -c$wpa_supplicant_conf $wpa_supplicant_if"

Make sure "wicd" service started long before "wpa_supplicant"

# rc-update add wicd default

mv /etc/runlevel/default/wicd /etc/runlevel/default/Awicd

rc-update add wpa_supplicant default

Gentoo linux 4.12.5 kernel configuration for 8188EU USB wireless adapter

Device Drivers  --->     [*] Network device support  --->             USB Network Adapters  --->            [*]   Wireless LAN  --->      [*] Staging drivers  --->               RealTek RTL8712U (RTL8192SU) Wireless LAN NIC driver             Realtek RTL8188EU Wireless LAN NIC driver