已经设置好了面板数据，数据已经都是数值型的，而且没有任何缺失数据，做普通的reg时也没有任何问题，就是做var时总是no observations,而且adf检验时也是这样很奇怪的结果，求问大神到底该如何解决啊

. . destring,replace

Date_Mon already numeric; no replace

Rt_0 already numeric; no replace

Vlm_0 already numeric; no replace

Tr_0 already numeric; no replace

chTr_0 already numeric; no replace

exTr_0 already numeric; no replace

Trs_0 already numeric; no replace

Mkt already numeric; no replace

SMB already numeric; no replace

Rf already numeric; no replace

HML already numeric; no replace

Stock already numeric; no replace

. xtfisher Rt_0

Fisher Test for panel unit root using an augmented Dicke

> y-Fuller test (0 lags)

Ho: unit root

         chi2(0)      =    0.0000

         Prob > chi2  =           .

. var  Rt_0 Tr_0 Vlm_0

no observations

r(2000);