I have the alfa 500 MW and use the default drivers provided by bt2 and bt3.
Drop wirelessassistant and use the command line.
Here are the commands I use.
1. Go to /etc/dhcpc ...and inside this folder DELETE EVERYTHING!
2. Ifconfig wlan0 down
3. iwconfig wlan0 essid "Xploitz Network" key c6e679d9a2
4. Ifconfig wlan0 up
5. dhcpcd wlan0
That should do the trick to get you internet connection.
If you want to use airodump and enable monitor mode.....
1. airmon-ng start wlan0 6 (for channel 6, put your channel of your AP here)
2. airodump-ng -c 6 wlan0 (again, my AP is on channel 6 so I used -c 6..put your AP's channel here)
Hope this helps!