Which VTF Scale are you using?

The digital scales can be off. I check them with little calibration weights.
The Ortofon I currently use is right on but it sits awkwardly on my gizmo so I ordered a Riverstone which should work better. It looks like a great product for the money. People here seem to like it.
The Musou is sold under 20 different names and costs anywhere from $12 to $129 for Pro-Ject's version. So much for exclusivity. 

The Wally Scale's claim to fame is measuring the VTF at record level. If you have a neutral balance tonearm it makes no difference whether the measurement is taken at record level or an inch above. VTF stays the same. Examples include the AR-XA, the Kuzma 4 Points, The Schroder CB and the Reed 2G. There are others I'm sure. To be a Neutral Balance arm the center of mass of the counterweight and the center of mass of the cartridge have to be in the same plane as the vertical bearing which ideally should be at record level. The center of mass of the cartridge will be above record level and the center of mass of the balance weight will be below record level. How do you tell functionally? Set the balance weight so the tonearm balances perfectly horizontally. Lift the head shell an inch and let go. Most tonearms will oscillate up and down looking for that balance point. A neutral balance arm will just stay there, an inch up.
No hunting. Neutral balance arms track irregularities in the record's surface much better leading to lower distortion levels.
Now there are many scales that measure at and around record levels like most of the ones mentioned above but a neutral balance arm has important benefits above and beyond a steady VTF anywhere within an inch of record level. 

Audite84 and vassilis, I hate to tell you this but the same scale is available on Amazon for $40.00 under the "HiFi Guy" name. The Chinese do this all the time. They design a gauge for Ortofon then either sell it to other people like Jelco or sell it themselves undercutting the price substantially. You have wandered into a perfect example. This scale also shares a lot in common with the Riverstone gauge. It would not surprise me if the internal mechanism is the same. The Pro-Ject is another example. Ortofon might tell you that theirs is "selected" for better tolerances which is doubtful. I have an Ortofon DS-1 which I am sure I overpaid for. It only reads down to 10ths which is also not good enough for the Gizmo.