Complex unit i in Comsol

Hi

I'd like to simulate a variable containing the complex unit i.

I'd like to calculate the voltage V = i*2*pi*f*S*B with i the complex unit.I read the docs and found that i and j are supported as complex units. So, I entered "i*2*pi*0.8540*mf.normB" as an expression in the simulation result. The problem is, I get 0 as a solution ( and I get a right value when I delete the "i"). So it seems there 's a problem with the complex unit i.

What is the right way to do so, please ?

Thanks