Circuit terminal question

Hi, All,

I'm trying to build a model four terminal nodes. Two of them are COMSOL voltage (terminal 1) and ground (terminal 0), another two is connected to 'external' resistor which is not defined as part of the multiphysics model.

Should I name the two terminal as type 'circuit', and name them 2,3? Then choose the nodes in electric circuit (cir) to be 2 and 3? What else should I do? I'm have an error says The DAE is structurally inconsistent .

Thanks!