Nissin Di 866 flash not working with 5d Classic

Hi i just bought a Nissin di866 flash.

The flash works with my 7D but not the 5D classic.

Can anyone help me out?

Thanks

wierd its working fine now. But it wasnt working before.

Theres a wierd whistling noise coming from the flash. Is that normal?

I have a Di866 which works great with my 20D and 50D.. I love that flash.

That "whistling" or buzzing noise is the capacitor charging up.. Quite normal.

Do I remember something about the Nissin flashes being firmware upgradeable? Did you look on their site and see if you need an upgrade for the 5Dc?

no need to upgrade. its just for the 5d2 on the old software that every time the flash fires at 1/1.

I used my 866 on the 5Dc. yes. it sometimes doesn't work... I think it has something to do with the hot shoe connection. I just remove the flash then reinsert it.