ABAQUS Thermal-Electric

[buru01003]

I am an Abaqus user and I am doing a thermal-electric simulation. In the simulation I give to an element an electric potential (Boundary condition) and want to know how the temperature increments. My problem is that in the simulation I program different Steps. In those steps I add by a model change more elements in the assembly. Those elemnts has to be TIED to the rest of the model and Abaqus says that TIE an POTENTIAL boundary conditions are NO CONSISTENT. How can I solve the problem of the TIE and the POTENTIAL boundary conditions?.

Thanks!