Sorry, can't help you except to suggest that you could email questions to the manufacturer (and hold on to your receipt in case you decide to return the gizmo).

Several people have reported here, over the past few years, that the "soil testers" they bought did not. The inexpensive pH meters seldom work and most read the same pH in soil, vinegar, or a baking soda solution. The only way to "calibrate" these is to clean them really well and then insert them in distilled water which should have a pH of 7.0.
Figure you just threw away what ever that cost.

I got it on clearance several weeks ago at Lowes. I think I paid $2-$3 for it. No big loss. Although, the moisture and light detection seem to work fine.. may keep it around for that. Ok.. how about the chemical(?) soil test kits. Anyone think those are worth a hoot? Of course, now that fall is here, I can't find them in the stores anywhere (sigh)

Chad

Think of it this way. Commercial growers, production nurseries, compost producers, etc. all send samples to commercial labs for testing. They all run on a tight budget and cut costs everywhere they possibly can. If there was such a thing as a cheap and easy test kit that actually gave accurate results, you bet they would all be using it rather than spending a nice healthy chunk on analytical work every year. But they don't. That's because cheap, fast and accurate simply does not exist. Your ag extension or county is the way to go. Or, if not available in your area, a commercial lab.

I got some of those test kits. They can't tell you a whole lot and are only marginally accurate at that. The ranges they read are high, medium and low. How well you can read them probably depends on the light you are reading them in. I took some samples that I sent in to the extension service what was left over I used to run through the home test kit myself.
The home test kit said the
pH neutral
Nitrogen Low
Phosphorus Med
Potassium Low

The extension service test said
pH 5.7
Phosphorus Very High
Potassium Low
Magnesium Very High
Calcium 966 ppm

FYI those electric ph testers are really only accurate if used exactly properly. The material being tested should be soil that has had debris removed (stones, sticks, organic material) will cause inaccurate readings. Then wet the soil and squeeze out all excess moisture, take the reading in this moist compacted soil. My understanding is that these meters are not meant to be dipped in liquid. The more accurate ones are the ones with a wire that runs from the meter to the probe and come with cleaning pads. I have the one with the double probe that does soil and light as well, I don't think it is accurate at all plus it doesn't come with the cleaning pad or proper instructions for getting accurate readings on pH.
I've also had trouble with pH testers for liquid. They start off working properly but now won't read anything but what the buffer/storage liquid is. I wound up making the hydroponic really acid before realizing the meter was malfunctioning.

"Although, the moisture and light detection seem to work fine"

One of those. I had one and was getting some odd results on pH that didn't seem to make sense. Until I noticed that I could alter the results in one spot by rotating the device or even standing in a different spot. A little experimentation showed that the pH meter was measuring the light.

I know a company which is pretty good at soil diagnostics (bodemverbetering). It is a dutch company, though they can probably give you some advice on this.