In the past my Gentoo failed to connect some wireless connection.
Today I run wpa_cli to check what the problem is, and saw this message: ``Association request to the driver failed''. It's obvious that I didn't install WEP driver.
So I enable the following option, and recompile the kernel:
Device Drivers ---> [*] Network device support ---> Wireless LAN ---> <*> IEEE 802.11 for Host AP (Prism2/2.5/3 and WEP/TKIP/CCMP)
After rebooting my Gentoo, the wireless network is successfully connected!
BTW: my pygtk doesn't work and I can't use ibus, so it's written in English :(