Hey, According to jessie's installation manual (this section -> https://www.debian.org/releases/jessie/amd64/ch04s03.html.en), in order to make a bootable USB stick it is necessary to copy the .iso directly into the device (/dev/sdX), instead of copying it to a partition (e.g., /dev/sdb1).
However, it's possible to allow the latter running isohybrid --partok iso-name.iso (according to isohybrid's man page), and I have done so, and it works. I wonder if there is a good reason this doesn't come as a default option? It makes things a lot easier. I think it also allows having multiple images in the same stick, selecting the one you want to use with the boot flag.
