Unless you have a different version of the test than the version I have, then yes, you're missing a reagent... Mine has 2, and here's the instructions (Even though you've found 'em, I found 'em so I'm posting 'em anyway! :wink: )
1. Add with 5ml syringe 1 ml of water in the test vial.
2. Add 6 drops of NH3-1 (watch out caustic!) and swirl gently for 5 seconds.
3. Add 6 drops of NH3-2 (watch out contains Mercury salts, wash hands after use, keep away from food, see additional warning under the heading WARNING). Swirl gently for 5 seconds and allow to stand for 5 minutes.
4. Hold the test vial and look through the side of the test vial. Keep the color chart behind the test vial. Ensure that a white piece of the color chart is behind the liquid layer. The values on the color chart are in mg/L total ammonia (that is NH3 + NH4+).