To troubleshoot: Make sure you put batteries in the recievers (the two bigger ones). Make sure they are On. Have them all on the same channel (the little white switches) Click the button on top of the transmitter (the smaller one) and see if it they work. Now install on your camera's hot shoe and see if it works.
They didn't work for me either. But that's ok. I'm using a ProMaster brand flash. Oddly, they did work perfectly with Nikon flashes that belong to friends. So, I sent the Cowboy Studio version back and ordered two more of different brands. The Trigmaster and Yongnuo. The TrigMaster didn't work either, but the Yongnuo DID. So I kept that set. I'm happy. It was a headache buying so many knowing I'd have to return them, but Amazon makes it so easy to return that I couldn't afford not to. You can troubleshoot until you turn blue, but either they work or they don't and you'll know instantly. With my setup, Yongnuo was the answer.