Hi, I am looking for an off-camera TTL cord for my 5D Mk4. I bought a cheap one from Amazon – a Kesoto for Canon DSLRs, but it doesn’t work on my Mk4 + 580 EX ll. It triggers the flash ok, but no E-TTL. I have searched the Internet, but they all seem to be for the 5D1, 2 or 3. Can anyone recommend one that works, with E-TTL, for the Mk4 before I make another dud purchase? Thanks.