Cannot create bootable USB for PCBSD

I've tried creating bootable for PCBSD using dd as mentioned on PCBSD website documentation and also in the Preinstall Instruction . I also tried "sync"-ing as mentioned here but it doesn't seem to work. I tried booting my laptop in both legacy and UEFI mode with secure boot disabled. Currently I'm using Kali Linux and when I restart my system with my USB drive plugged in, it simply goes to GRUB menu with Kali to choose. When I type F12 on my dell laptop to enter boot options on startup I do not see my USB drive in my boot options. Any idea? PS : I'm also sure that the image file was properly downloaded because the same image file works fine in virtualbox.