Audio Additives Stylus Force Gauge inconstantcy

I recently purchased an Audio Additives Stylus Force Gauge and it is driving me nuts. I get inconstant readings every time I lower the stylus onto the little black dot on the plate. Without moving the arm, every time I lower, raise, lower, etc., I get a different reading between 1.68 - 1.88. The batteries are new, device reads 0.000g at start up, calibration checks out using supplied weight, room temperature is 72F, no interference from tonearm lifter and everything is level.
Anyone else have this problem?
Exactly Larryi.

I never even thought about the magnetic part of measuring on the outrigger bracket, just the fact that it now sits at correct height but it certainly could be a part of it.
To the OP:  Lower the cartridge (preferably an MC cartridge, because they have big magnets) until it is barely above the weigh pan but not touching it. Does the gauge show a negative weight value?  If so, that indicates it contains some low level of iron; the magnet in the cartridge is pulling UP on the pan.  If the weigh pan is magnetic, even a little bit, that messes things up.  I used one of the popular digital scales for years before realizing that it had the problem, which was only evident when I tried to adjust VTF for an Ortofon MC2000 cartridge, which has a humongous magnet situated in its belly, near to the platter or any weigh pan.  I subsequently bought one of the 2 or 3 gauges made by Ortofon, the weigh pan of which so far seems to be non-ferrous, although it is metal.  This problem seems so easy to avoid in designing such a gauge.  But apparently the sellers do not care a fig.  As long as they're selling.
I still use the old Technics that came with the EPA-100 arm. It's electronic but analog, not digital, and doesn't give you milligrams (which are SO important). It's just a needle that swings from .5g to 3g, with markings for each .1g — and I can squeeze the needle between them for .05g. Accurate enough for me, and utterly consistent. Not high tech, but cool in a retro way. 
That is a very big discrepancy; it’s normal to have some minor discrepancy with any of these gauges and especially those that have 3 decimal point resolution but that is huge. Also, try to hit the centre of the dot each time.

In light of the fact that scale takes triple A batteries, I would replace the batteries first to see if that might fix the problem if you are using those that came with the scale. You may already have some extras around; if that doesn’t correct things then, yes, look for a new scale.

The body of the Riverstone gauge---they actually make two, but get the one with the extension arm which puts the stylus at playing height when measuring VTF---is made of a tough plastic, and that extension arm of a non-ferromagnetic grade of stainless steel. The gauge has resolution to 0.005g (!), and can be recalibrated to zero via the 5 and 20 gram weights included. Riverstone Audio has a video on You Tube in which the gauge is displayed, described, and explained, and then demonstrated.

The ubiquitous electronic gauge that most companies are rebranding and marketing as their own is, in comparison, a piece of junk, regardless of price. Many of them sell for more than the Riverstone, some much more. I mean come on, $28.95---whaddaya got ta lose?! For more details, see the Riverstone Audio website.