Here's what I recommend to anyone using an API test kit.... the ammo test is never going to be as yellow as the color on the card. What you are looking for is more of a "lack of green" rather than that bright yellow they depict.
Either make sure your RODI water is truely 0 TDS, or go spend a couple bucks and get yourself a gallon of distilled water from the grocery, and mix up some salt water to your specifications. Now run two ammo tests side-by-side, one with tank water, and one with the control sample of known clean water..... if they come up the same color, you have no ammo. If your tank has been up & running for a few years, I'm venturing a guess and saying no have no ammo, it's just the way you're reading the test.
One other question.... If you're using an API test kit, how are you getting 0.01 Nitrite when the test reads in 0.25 increments up to 1ppm?
EDIT: just went back & saw that you are using distilled for your pwc's, so do the above with your mixed water. Another note.... It may seem cheap to buy a few gallons of distilled water at a time, but if you add those up over the long haul, you will come out far cheaper in the end to pick yourself up an RODI unit.