Probably. If you have high FC the colors can be weak.
You might also be getting some interference; the way around it is to add a few drops (count how many) R-0012 first, then run the test normally, including the first few drops in your count.
I hope you were using a speedstir for that 60 drop test!
I use a 10ml sample and each drop is then worth 25ppm. Saves time, saves reagent, and I really don't care if I'm 600, 610, or 625. At that level, it's not a big deal.