It just takes time
This is for all of the newer DT contributors out there. I know it can be a frustratingly slow process at first. You have to get signed up, figure out how to submit photos, figure out what gets accepted and what does not, and figure out what sells and what does not. Then you start getting some sales. Maybe 1 or 2 the first month and 3 or 4 the second but nothing steady that you can take to the bank.
All I can say is stick with it. It will pay off. I have been with DT since February 2010 and I am getting ready for my third payout. The first payout took a year, the second 6 months, and the third about 3 months. The more photos I upload the better it gets.
My goal right now is to get to 300 images online and a payout every month.
Keep it up. Hard work does payoff.
For example, here is an illustration, one of my first, that I uploaded almost 10 months ago. I got my first sale of this image today.
Photo credits: Mvogel.