土固结分析中出现的错误

DEGREE OF FREEDOM 8 AND AT LEAST ONE OF DEGREES OF FREEDOM 1 THRU 6 MUST BE ACTIVE IN THE MODEL FOR *SOILS. CHECK THE PROCEDURE AND ELEMENT TYPES USED IN THIS MODEL.在提交工作时，出现上述error，不知道是什么原因，请高手赐教，谢谢