It's weird but whenever I run ettercap -G and ifconfig only lo comes up. My wireless card is nowhere to be seen. Although when I try to view it using
I can see my wireless card wlan0 clearly written on the screen.

I'm using BackTrack 4 (pre) Final on LiveCD booted through USB. I copied the LiveCD using unetbootin. My main OS is a LinuxMint 8 x64. So far I have no problems doing everything above in LinuxMint.