Problem with unit configuration

[Stergioulas]

When I try to make a manufacturing order or use the inventory I get the message “please configure unit conversion from grams to kilograms” the formula method unfortunately hasn’t worked for me, neither changing the products manually to kilograms. I am using the online demo. The formula I have used is this one:
Start unit: g
End unit: kg
$Product.netMass$ / 1000
Maybe I am doing it wrong could someone please help? Thank you !