I got the same thing you did I think. Did it come in a white bottle with green lettering?

It seemed to work for me in the 4KH reference sol'n, but it's tough to tell exactly what pH you're at since each color change indicates a 1 pH step.

I just changed out to bromo blue last night and I think its easier to get a more accurate reading with it.

At 30 ppm CO2 in 4Kh solution you will have a pH of 6.6 which is right in the good range for bromo blue.