Can't bootcamp with iso flash drive. Please Help

Alright, so I decided to bootcamp (Macbook Pro 13" Early 2011), and have downloaded the iso image of Windows 7. My computer does have an optical drive therefore I am not given the option to make a bootable iso disk. However, I was able to make on with an iMac as well as have made one on a PC. Every single time I go through (or attempt to) the process of installing Windows the flash drive is not recognized as a bootable disk. I am able to get to the point in bootcamp assistant where I select the partitions, however as soon as I click "install" I am given the message "please insert your windows installer disk and wait a few moments for the disk to be recognized." The flash drive is in, and as stated above, I've made one on an iMac with bootcamp assistant and one on a PC and neither have worked. Is there an option in bootcamp assisant that I'm missing that allows it to boot from a flash drive? I did find out that since my Mac has an optical drive it did not allow me the option to make an iso flash drive, hence the reason for making them on the iMac and PC. Some help would be much appreciated as I really need to bootcamp this machine as I need to begin running Windows programs and no, I don't want to use Parallels.