With a NEC atheros 5212 chipset card using madwifi-ng 126.96.36.199.2~rc1 and wlassistant 0.5.7, wlassistant fails to connect to wpa_supplicant with the message:
"Failed to connect to wpa_supplicant - wpa_ctrl_open: No such file or directory"
This appears to be because wlassistant is using the wrong driver when calling wpa_supplicant, as it echoes:
"Using wpa_supplicant driver: wext"
Just before that.
Calling wpa_supplicant manually using wlassistant's configuration file like so:
wpa_supplicant -Dmadwifi -iath0 -c/root/.kde/share/config/wlassistant
succeeds in starting up a working connection.