1D2n Problem with 580ex2

So lately I've been noticing that my flash doesn't quite work with my mk2n.
the only time it works is when its at an angle, I have two 580ex2 and they both work when only tilted to the right. Both my flash works just fine with the 5d2. Do you guys have any experience like these? Any remedy for this problem?

Sounds like the hotshoe on the 1d is loose and not keeping a good connection with the flash. There are some small screws under the spring plate in the hotshoe. Remove the plate and tighten the screws.

What Dale said.