install windown7 from usb pen error
===

I tried to install windows7 from USB according to the instructions of following page.
    http://www.intowindows.com/how-to-install-windows-7vista-from-usb-drive-detailed-100-working-guide/

But at the location where i select the partition it says me something like "device not found."(Cant give the exact machine as i came to somewhere else to search the internet, coz my machine's not working).

How can i overcome this?? I've formatted the whole disk. Got nothing to do now!!!