'No bootable disk' error message when installing Windows7 with Bootcamp

Hey,

It seems so many people have had this problem which I am having now, I've tried searching for a solution that works but to no avail. So I'll give as much detail to this problem in the hope that someone knows the answer!

When running bootcamp assistant in order to install Windows 7 on my MacBook Pro (running Lion), I am able to go through all the steps - create USB installer, download software and partition hard drive. However, when the computer restarts I am faced with the black screen displaying "No bootable device - insert disk and press any key to continue". Nothing seems to work!

I've tried using a DVD instead of a usb to install Windows, using a burned copy of the ISO disk image (in UDF format) of Windows and I've tried using a sony and a san disk USB. I've tried holding down the option key on start up to see if I can select the disk manually but nothing appears (just my hard drive and the recovery mode).

Any help would be really appreciated! I'm in need of windows in order to run some programs to carry out data analysis on endangered species for research.