Antenna simulation error in CADFEKO

I imported antenna geometry from HFSS to CADFEKO, I am new to FEKO and trying to implement coax probe feed excitation in CADFEKO by using waveguide port and waveguide source by selecting the face of the coax dielectric at the base and then defining the excitation. Even though according to me there is no geometry clash but it shows geometry clash in the software for my structure and I even tried using smaller custom mesh but I am getting the following error when I am trying to simulate the antenna :
Triangle 1: 16 (Medium: 0)
Triangle 2: 1372 (Medium: 3)
ERROR 38878: Expecting two adjacent triangles at a junction to share a region medium. Please check the mesh for consistency in the triangle normals/media

I am not able to see these two specific triangles in mesh hence unable to understand in detail what is actually causing the error. How do I see which mesh triangles are causing the problems in CAD? Also, How do you create and define coax feed excitation in FEKO? I read about A4 card but could not implement it yet. Please guide me.
Thanks.