Install windows 7 from USB on bootcamp

HI all !!!

FIrstly, i had an iMac which running OSX 10.7.4 and it was made in mid 2010. Now its superdrive can't read whatever the disc is while it show only that disc is a blank disk.

I wanna install windows 7 on bootcamp rather than on other VM so after i start bootcamp assistant i see a gray on create a windows 7 install disk but after a few research i can make it enable and i had make a bootable window 7 usb with it. After that i start divide the partition and when it bootup, it said no bootable disc.

Can anyknow tell me what the problem with my super drive? And why bootcamp can't boot from the usb that i make by boocamp assistant?