Wlandecrypter is a program to decipher very quickly wireless networks with the name WLAN_XX (XX are two hexadecimal digits). These networks are typical of IMAGENIO router. only for TELEFONICA routers.
I recommend to install wepattack with wlandecrypter.
firstly catch 1 or more data packet with airodump-ng and next put in a terminal:
wlandecrypter bssid essid | wepattack -f file.cap
*bssid (machine attacked)
*essid ( machine attacked, WLAN_XX).
*file.cap the file created with airodump-ng