PML Error: Could not find any cartesian regions

Hi

I am new to PML. I am using Structural mechanics module to implement PML in a cantliver to determine the waves propagating to the PML. I am getting this error: Could not find any cartesian regions. My dimensions are in micro meter but using conversions to use it in meters. Please suggest what am I missing here.

Is there any model on PML using SM module?
Thank you.