Persistence partition makes USB unbootable?

[Synaxr]

Hi there.

For quite some time now I tried to make a persistent Kali USB for my Macbook Pro since a hard install proved no good. There's no problem with using the dd command to install the image on my USB and it boots into Live Mode quite happily. The problem now is the persistence. I followed a number of tutorials which had me do the following:
1. After install, allocate unused space as new partition labeled "persistence"
2. mkdir -p /mnt/usb
3. mount /dev/sdb3 /mnt/usb
4. echo "/ union" > /mnt/usb/persistence.conf
5. umount /dev/sdb3

When I now restart the system and try to boot up (not using rEFInd due to some weird bug that causes it not to load during boot) the stick, either the "Windows" option does not appear at all or when trying to start, spits out the error "No bootable medium found -- please enter a stick and press any key". Now I have to reformat my stick and wait for half an hour to copy the image again and I fear that if I repeat those steps, it will break again? Any help would be great!

[Synaxr]

Et voila.

It works. Why? I have no clue. Here's what I did: Back back to Yosemite, formatted the stick entire (as I did before). Did the whole dd againa and this time followed the commands on the Kali Documentation site. I must say that it wasn't that much different from what I did before since I skipped the manual partition creation. Either way, the persistence works like a charm and it does actually boot, however only from the one USB port that the stick was NOT created on? Meh, it works, I'm satisfied.

[Link_ali]

Which guide did you follow?

Was it this one:
http://docs.kali.org/downloading/kal...ve-usb-install

So that's all you did? I'm having trouble trying to create a persistent live usb on Mac myself.