Dell e7240 - Still waiting for root device

Hello,

So I have a Dell Latitude e7240 (i7-4600u, 8gb ram, 256gb liteon ssd). When I try to boot from an OSX usb (El Capitan) made with Unibeast 6 I got the stop symbol. When I run with -V boot flag is says "Still waiting for root device" and freezes. What are some things I can do to troubleshoot this? I have tried Googling and have set SATA to ACHI and disabled secure boot. Any other ideas?