Co2 drop check help!!!

inject more co2
or make sure u have 4 dkh solution and proper ph reagent added

If the drop checker liquid is not colored, you didn't add the API pH reagent - about 2-4 drops, which makes the liquid dark blue before you put the drop checker in the tank.

The hight ph or low ph??

Aquarium Pharmaceuticals Inc. (API) low range pH test is the one - measuring from about 5.5 to 7.5 pH, with colors from yellow to blue.

Also, What did you put inside the drop checker? Just tank water? Make sure you use 4 dKh solution as mentioned earlier. Then some drops of pH regent.