我把三年CHFS数据用mi xtset合成了面板数据，然后想做一个工具变量回归，但是xtivreg命令无法运行，只显示如下结果:
xtivreg zc hznx hzjy hzyh jkbz  hznl  lnjtzc (index_aggregate=distance),fe

no; data are mi set
    Use mi xtset to set or query these data; mi xtset has the same syntax
    as xtset.

    Perhaps you did not type xtset.  Some commands call xtset to obtain
    information about the settings.  In that case, that command is not
    appropriate for running directly on mi data.  Use mi extract to select
    the data on which you want to run the command, which is probably m=0.


请问如何解决呢？（想过附上代码，但是不知道应该截取哪一段）