How to sweep through different boundary conditions using parametric solver

Hi,

I am investigating the current distribution in water, it requires me to send a voltage into a medium (water) through an electrode and measure through another electrode.
My problem is how to change the boundary condition (i.e. Electric Potential) using parametric sweep. I have tried using using the tag ({pot1}) to reference the parameter names in parametric sweep and using the selections within the parameter value list (grouped the boundary condition using Explicit (Definitions)).

Many thanks,
A.Onilude