windows 7 on usb problem

InbeforeSEARCH

late 2011 13" base macbook air w/ refit

Working windows 7 on pny "attache" 8gb usb drive

what I have tried:

bootcamp ver of windows 7 usb
windows usb program
command prompt


every version of the usb stick has netted the same result (with and without the use of refit)

"no bootable device found"

I know the iso is good b/c it was a paid for direct dl from microsoft. That leads me to believe that some usb drives just don't work as bootable devices.