i had the same problem and solved now. undergo the undermentioned steps:-
1. connect your wifi device to your computer through a cable (cable is provided to you when you buy your wifi device.
2. now you are connected to the internet.
3. enter the configuration ip address of your device in the site bar.,.,., for example it is 192.168.15.1 in case of witribe
4. enter username and password
5. go to network setting--> WLAN-->SSID WPA settings
6. set the cipher type key to TKIP and change your pre-shared key
7. now when settings are saved, remove the cable and connect to your wifi with your new set key.
8. hope it helps you