I have a MacBook Pro 13' retina from April 2013. Yesterday I wanted to do a clean install of Yosemite. I formatted my USB as
Mac OS Extended (Journaled) and made the partition to be a GUID table partition.
Then I run this command to copy the bootable installation files of Yosemite to the USB:
sudo /Applications/Install\ OS\ X\ Yosemite.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled --applicationpath /Applications/Install\ OS\ X\ Yosemite.app --nointeraction
Everything went fine and to be sure I verified with Finder that the installation really was in the USB and not corrupted.
Then I rebooted my MacBook Pro, held the Options Button to get into the boot menu but there my USB wasn´t listed, only the harddrive and the recovery partition. I also tried the other USB port but id did not help. I have googled a lot of this issue but I haven´t found anything that helped. I have also tried the whole procedure of formatting the USB and putting the installation files 3 or 4 times now.
After some hours of tries to boot the USB I gave up. What I did instead was to open Disk Utilties (from my recovery partition) and format the harddrive, then install Mountain Lion and then make the upgrade to Yosemite. But that is not a clean install.
Any ideas why I could not boot from the USB?