Cannot boot from USB stick on a T3600 please help

Hi I need to boot DOS from a usb stick. I've tried three different sticks and it fails. I have used several progams to create a bootable usb drive with DOS and it fails. I've been in the bios and changed the settings all of them that are relevant and it will not boot....it says selected boot device failed, restart or something similar.

I have tried the dell diagnostics program on usb and that fails as well.