I must ask, are you sure you are performing the water tests correctly?....see below for simplified instructions for each test.
Regarding the nitrAte test, it is imperative that you shake the 2nd bottle of reagent like mad before adding to the TT....shake hard for several minutes, bang the bottle on a desk, shake upside down, and shake some more....if you do not shake the 2nd bottle enough, you'll get false readings for nitrAte (usually 0)
AMMONIA:
8 DROPS FROM BOTTLE 1, 8 DROPS FROM BOTTLE 2, SHAKE 5 SECONDS, WAIT 5 MINUTES.
NITRATE:
10 DROPS FROM BOTTLE 1, INVERT TO MIX, SHAKE VIGOROUSLY SHAKE BOTTLE 2, 30 SECONDS OR MORE, 10 DROPS FROM BOTTLE 2, SHAKE HARD FOR 1 MINUTE, WAIT 5 MINUTES.
PH:
3 DROPS, INVERT TO MIX, RESULTS ARE IMMEDIATE.
NITRITE:
5 DROPS, SHAKE 5 SECONDS, WAIT 5 MINUTES.
HIGH PH:
5 DROPS, INVERT TO MIX, RESULTS ARE IMMEDIATE.