hfss simulation port problem

Hi all,

I explain my problem : I want to extract S parameters of a part of a transistor package, and that's why I describe the all structure in HFSS and assigned all materials with correct parameters.
After checking all is ok, I put the first lumped port on the input pad and the second one on the bondpost pad. When i simulate the following error occured : "port refinement : abc3d : subprocess wave encountered error in second point addition"

I don't know if the problem is located on meshing process, anybody could help me ?

Thanks