求助！请教论文各位前辈，使用tobit模型对数据进行回归，想加个省份固定效应，但是系统一直报错，显示r(119)no; data are mi set
    Use mi fvset to set or query these data; mi fvset has the same syntax as fvset.

    Perhaps you did not type fvset.  Some commands call fvset 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.
r(119);


我使用的是截面数据，是调查问卷来的。回归代码如下：
tobit R_Tdebt ln_quant1 ln_pregdp Secondary_sector Tertiary_sector investment age2 Risk_appetit age i.prov_ , ll(0) vce(cluster prov_)
就是加了省份固定后不行了，请各位前辈赐教！！