Thermal contact resistance

Hello,
I'm trying to model a thermal sensor in contact with a solid. To do this, I need to embed a heat source in one material and then see the heat flow into a second material. I also need to account for the thermal contact resistance between the two solids.
I understand that I can create a 'contact pair' and then set this to have a boundary condition of 'thin thermally resistive layer'. However, I am struggling beyond this as I get an error message:
Error: 6170
Failed to evaluate variable
Variable contact_cp1

I am unsure about using contact pairs and I'm obviously missing a step out. Does anyone know of an example for using contact pairs, or can offer advice on modelling thermal contact resistance in comsol?


Thanks,
Joe