ansys接触问题求教

利用MPC技术对SOLID-SHELL单元进行连接实例时，生成附加的虚拟壳单元出现以下警告是怎么回事？With SHSD the behavior of contact surface must be bonded .KOP(12)=3 is then not valid for CONTA175.The SHSD command is ignored for real ID 2.