Flight controller and clean flight. What am I doing wrong.

Okay I'm on my first build and I'm stuck at my flight controller. I have a brand new full naze 32 and I'm trying to flash clean flight on there and I understand I have to get the other firmware off.

So I bought a naze 32 rev 6 full and it says "no response from the bootloader, program failed". I tried every possible thing I could find on the Internet and couldn't get it to go. So my next step was to buy a naze 32 rev 5....so I did, I plug it into my computer right out of the box and get the same message. Is there a problem because I'm using a mac.

I have watched youtube, read threads, and tried over and over. Am I missing something? I have spent so much time on this build just on research. The hands on build is fast and easy too bad that's the fun part for me. But I just can't figure this one out. So any help with These flight controllers would be great I'm starting to get pissed.

Thanx in advance