Generating Port in PowerSI: Error "Failed to generate ports for circuit: No Negative Terminal"

Hi All,

I am trying to generate a S-parameter File of a PCB Transmission line for a C-PHY channel. The PCB is easy (as shown below). The port are 7 A_in, B_in & C_in and A_out, B_out &C_out + GND

The final goal is to use it in Virtuoso to simulate a High Speed TL using the nport cell from AnalogLib

My Question: I am trying to generate the 7 ports, but I was uncapable. I was following the videos from Prof. Om Mandhana and the user guide. I am able to create the PCB with KiCad and export it to PowerSI... but no solution.

Any hint, link to a resource or idea on how to proceed?

Thanks a lot!! :)
Albert