hfss v12 differential port setting problem

Hi, All

When I simulate a 8 traces with hfss v12, a error message is shown as follow: Port refinement, process hf3d error: Too few conductors were found on port 1. There should be one conductor for each terminal, with one additional reference conductor. Unintentional contact between conductors may cause this error..

Could someone help me to solve it.
Thank you very much.

Hi,
In my case, Air box was helpful.