You need to drop your reps, like healthfreak said, and go heavy. I find 4-8 reps is where its at, when going to failure, in getting delts to grow. Just make sure your forcing yourself to get stronger each week while doing this. Here is a good routine; if your eating like a horse, and getting proper rest, your delts WILL grow.
Seated DB military press - 4 to 5 sets- 4-8 reps, with one set, either your first or last, 10-14 reps.
Dumbell Front Raise - 3 sets- Keep your rep range between 4-8, but have one set with higher reps in the range of 10-14, either for your first set or last, to really get a deep burn.
Dumbell Side Lateral Raises - 3 sets-
Rear Delt Machine, or Rear Dumbell Lateral Raise - 3 sets-
I assume your bulking, so this routine will work well on a high calorie diet. It is high in volume, but works really well. Make sure to take as many sets to failure as you can, and track your workouts to improve every time you step foot in the gym. I guarantee this will get your delts to grow. Do your shrugs on another day, or you will over-train. Keep your shoulder workout seperate from your other muscle groups