Bummer

I just got a rejection from one of the microstock agencies, because of poor lighting with one of my pictures. Here it is:



It's a little frustrating, because I'm having trouble understanding what constitutes "poor lighting". I'm trying to understand what makes a good stock photo, and I'm not sure where to get the answers. I'm doing on online stock photo program, so maybe that will help. Perhaps too, I can study the Lightroom book more closely. But I've done it, and now I just have to keep trying.