Questions about: live-environment

Trying to install from a USB live image and getting the following - [ 26. 952015] ata3: COMRESET failed (erro=16) BusyBox v1. 21
If you select "USB" and "Mac" on this download page, it gives a series of command line instructions to make a USB key which the MacBook will boot into Ubuntu from. I've followed them to the letter two or three times on different USB keys, and it does