Boost gauge reading all over the place

[Zak.p]

Boost gauge reading completely off, installed all the new wires which come with it into the exact places as the previous boost gauge and that was working fine (same brand and model)

this says -0.5 to -1bar boost on idle and when boosting it is nowhere near right either, defo not the car as the other gauge was working fine, any help appreciated

[Gainzy]

Put the old gauge back in

[Zak.p]

Now that it's wired for the new one the old ones is off completely as well lol

[JamesD89]

It should be showing minus on idle as its under vacuum

[Zak.p]

Even when on boost the reading is completely off but I know the boost is spot on set to .8bar as the old gauge showed this not sure why it's all over the place now