For download application, we must: 1. Download Now Click Download Now to begin downloading application 2. When finished, there will be the .dmg file to your desktop (or Downloads folder). Then double click the application for Mac file to begin installation. At first, I always do that ways to get many applications. There is no problem. I just download, then install it. Very simple. But, I think now there is problem with my mac. After doing the first step, I cannot do the step 2. When I double click on the application, there is no installation begin (nothing happens). Why does this happen?