此類錯誤可能的原因是什麼

Vanity antenna01 (E:/ansoft hfss10.0/)
  HFSSDesign1
    [error] Port refinement, process abc3d : There are no boundaries to define "LumpPort1" correctly.  This may be due to incorrect material definitions for those objects that make up the port surface.  Please verify the material assignments and properties. (3:45 �Uと
    [error] Simulation completed with execution error on server: Local Machine. (3:45 �Uと  �@る 07, 2009)