no there is no command, but there are drivers. i suggest installing uBuntu instead. your laptop was a big mess, i suggest format it and put xp + ubuntu on it as dual boot, if you want to make it a powerful cracking and hacking tool.
i assume you are testing it on laptop, i remember that backtrack4 didn't even detect your internal adapter on some reason.
anyways try if USB stick works fine in windows (any windows). if so, then you need drivers.
ubuntu should install them manually.
also give more info, what usb it is ? it might be some compatibility problem, check http://www.aircrack-ng.org
and search for the list.
registering and asking a question on their forum is quite pointless, they are full of themselves and won't really help, they just say "google" or "read wiki" .. thats dumb.
however its not so hard to find the compatibility list on their site. its a hassle, i know, but this is how cracking and hacking is.
1. find out what chipset your USB card has (manufacturer doesn't matter, just the chipset)
2. go to http://www.aircrack-ng.org
and find out if your chipset is supported (it might be supported on windows, but i doubt).
3. either get right drivers from http://www.aircrack-ng.org
or install ubuntu and see if it install them.
4. in ubuntu get "aircrack-ng" suite, using synaptic packet manager.