Well everyrhing works but after it said backtrack3 is succefullt installed, the usb just contains a 1kb file with the name boot...

Thanks for the answers

Another question,

I use shaman virtuels program to install it but the only thing i get is a 1kb file with the name boot it took like a sec to finish...so what should i do?

Well i was wondering does it matter how much GB the USB has ?
cause i only have a 8GB USB and i'm almost sure that it will be rather slow but i still would like an answer