Looking for some help with my sync cord problems.


I have a 40d, 580 EX II, and a Screwlock PC Flash Sync Cord (from Flash Zebra)


The Problem...


I keep having issues with my flash not firing, but it happens randomly.


I have tried to think of everything that could be wrong but then all of a sudden it starts working again. I don't think that anything is loose...


It drives me insane when I am on a shoot!


any thoughts?


Thx