gh indicator does not change to green

[WaterH2O]

Hi

I recently brought a Aquarium Parmacueticals GH test kit to test my new tank water. Instruction given is to add in the chemical drop by drop into the test viral containing the aquarium water that I am trying to test. when the test water turns from orange to green and that is the end of the test. The no of drops will be the GH of the water in oGH.
Problem is when I add in the first drop the water is still clear but when I drop in the second the colour changes a bit to yellowish instead of orange. The more I drop the color does not change much and it still looks more yellowish rather than orange. The worst thing is that it remain in this yellowish colour even after I have added about more than 15 drops. It does not change to green. Any idea? Can the water be that Hard?

[WaterH2O]

Anyone of you here has ever used a GH tester. I brought 2 kits one by API and the other by Tetra but both do not change colour as what was indicated by in the instruction sheet.
The API kit says will change from Orange to Green (endpoint) but the colour change to more yellowish after about 4 drops.
The same goes with the Tetra test kit, instruction says colour will change from Red to green (endpoint) but the colour change also the same as the API kit which is more yellowish after about 4 drops.

Adding more drops to the test viral does not change colour and it remains more yellowish than what it says in the sheet. What worng with my water? Will not increase/decrease my GH unless I can understand waht is happneing. Any idea from the experts?

[ct13]

I bought the API gH test kit too few weeks ago, no matter how much I add the gH up in my tank. The test kit turn green straight after the first drop.

Had throw the test kit away since then.

[WaterH2O]

One thing I noticed on this forum. Not much were mentioned about GH test kits. I can find thread on PH, KH, Ammonia and Nitrates test kits but not much on GH test kits. Strange. The one only reason I can think of is not many of us here use it.
Am I right?