Windows 7 boot key not showing up in boot menu.

I have installed the Windows 7 ISO to a flash drive to use on boot up, using the instructions here: https://discussions.apple.com/thread/5488789?tstart=0

I have a Late 2009 iMac and the optical drive is broken; that's why I had to use those instructions and intend to use a boot key. However, when I boot up with the option key, the only options presented are Macintosh HD and Recovery HD. No Windows boot or EFI boot to be found. Does anyone know why this might be? I have gone through the partitioning process in Boot Camp Assistant. I really don't know why it's not showing up. Any help is appreciated. Thanks.

Screenshot provided for reference.