Cannot Boot From USB (Can't Find Mach_Kernel)

[theprovost]

I'm trying to upgrade from Snow Leopard to El Capitan by creating a boot key with Unibeast. The key seems to create just fine, but my computer says there's No Bootable Device Found when I try to boot from USB. If I go to the Chimera menu (I think that's the one Snow Leopard uses) and select the USB drive from there it says Can't Find Mach_Kernel and brings me back to the menu.

I've tried two different USB drives (an 8GB and 60GB) and they both have the same issue. Am I missing something? I'm selecting the following options:

- El Capitan
- Legacy Boot
- No Video Drivers

 

[theprovost]

I did try removing the org.chamelon.boot.plist file as someone else had suggested, but that didn't help and made SL hang when booting. Thankfully I was able to restore it by booting through iBoot.