How to change units in a formula

Hello,

I have different signals with different units (mA, V…). I would like to convert them in %.

I do a formula, for instance for the new signal Current% from a signal Current in mA : (Current-4)/16*100

At first Current% is still in mA. So I go to the property editor and I replace Y unit by %.

But it does not work : units’s incompatibility problem.

How to fix it ?

Thx

NB : In the unit manager menu, I have no units control.