One thing I've found with these cords is that they are a bit short and the coiling is quite strong. The result is that the plug can pull out of the battery or the flash. The way to keep it in the battery is to be sure to engage the lock around the plug. The way to keep it in the speedlite is to loop it around the lens to take the pulling pressure off the plug. I put the battery on my belt on my left side. As I'm writing this I realize that if I put the battery on my right side it would also help to minimize pulling tension that loosens the plug from the speedlite.This is the one I got - http://www.amazon.com/gp/product/B00DGLTGMI
With Canon I found some cables from Paramount that solved the problem because they are longer and not as tightly coiled. I've looked but apparently they don't make a cable for Sony.
I did notice there is a Phottix cable for Sony that looks to be lighter weight. I may get one of those to try.