bootcamp mac won't boot from usb

Hi

I just created a bootable usb with bootcamp. I am trying to run windows 7an am currently running Mavericks . I created the usb stick on boot camp no problem. But when I try to boot from it it freezes. I think the usb drives loose power because the caps lock button won't turn green if i push it. The usb stick light doesn't even try to flash it is just dead. I don't even have an idea what might be wrong.

Thank you any help is appreciated.🙂