|yes, you have captured the action of a sport here, and you should get points for that. if this isn't scoring high enough for you, here's some ideas about this picture and the challenge:
1) try to get more people in the picture
2) try a different perspective (like moving closer to a pole, and shooting down the net).
3) if your camera has the controls, use them to focus on the subject, but to blur the background
the thing to do with these challenges is to shoot a lot. and i mean A LOT. even if you aren't thinking about challenges--SHOOT A LOT! practice is the only way you will learn to control your camera and how to compose and capture great and interesting images. if you are shooting for a challenge, try lots of different ideas. if you are out simply shooting, keep the challenges in the back of your mind, but shoot like crazy--then, hopefully, you'll wind up with a shot that can do well in the challenge. the biggest mistake you can make, though, is to simply quit...
better luck next time!