Editors, of course, get busy, and unless you're a superstar, the chances that they're going to drop everything to get back to you are pretty low. Unless the matter is of critical importance, they'll get to you when they get to you. Fallow times for ideas and writing progress come with being human, and building a reputation and a writing career is seldom accomplished with just one or two books.
As with so many things, patience, perseverance, and a healthy belief in oneself are the keys to getting past these frustrating times and continuing to write. The first two, I'll admit, are not qualities I particularly enjoy exercising. Nonetheless, they are necessary and part of my journey. And should you also be stuck in the Dead Zone, don't give up---you, too, have a journey to make and a story to tell.