plate capacitor in frequency domain emf

Hi,

I built a model of a simple two plate capacitor and I want to compute the capacitance in frequency domain with the emf interface.

I built two plates, set the material to copper, created a surrounding air and set one plate to "terminal" and one plate to "ground"

But something seems to be wrong with this model. There is no electrical potential field in the Air domain after computing the study. And the admittance is only a negative real value (see the values stored in the table ).

Maybe someone could give me a hint whats wrong with this model ?