A hydraulic fluid having the index 0 has not been defined

我利用AMESim中自带的汽车整车模型，然后在里面添加液压制动装置，然后仿真出现一个问题“A hydraulic fluid having the index 0 has not been defined.
AMESim model D:/yeyajixie20100421_ did an abnormal exit”，请问是怎么回事，这个index of hydraulic fluid是什么意思，该怎么设置。