Cant boot Kali USB with Grub

[gre4twhite]

Hi, I currently dual boot windows 8.1 and Linux mint 17 so grub2 is my boot loader. I created a bootable kali usb using universal installer from pendrivelinux and using the DD command in linux shell (I've tried both). However, I cannot boot from usb on grub. I use the command set root=(hd0), which is my usb, but when I enter "chainloader +1" I get "does not contain a valid EFI filesystem". I have tried the EFI bootable kali tutorial here "https://forums.kali.org/showthread.php?271-How-to-EFI-install-Kali-Linux" but I still get the same error in grub when trying to boot the usb. Has anyone had this problem that can help?

[brtp]

Don't know if this will help but I had the same problem with a little bit different set up however I booted to my linux harddrive used "disks" to make sure usb was bootable. then used testdisks to make a new mbr for the usb and finally ran update-grub to see if it was recognized

not sure if all the steps are necessary but it worked for me