[22718] We were unable to copy your files. Please check your USB device and the selected ISO file and try again. {copied from codeplex}

[stadub]

This error happens when the USB stick already have something in its MBR, which WUDT doesn't CLEAR.
The workaraund (proposed in this post http://4sysops.com/archives/windows-7-usbdvd-download-tool-wudt-is-unable-to-copy-files/ ) is to use the diskpart utility to issue the clean command on the disk, which cleans the MBR.
It works!
The commands are:

diskpart
list disk
select disk #
clean
create partition primary
select partition 1
active
format quick fs=fat32\nassign\nexit

LastUpdatedDate: 2016-08-03T16:39:08.66-07:00

[stadub]