我的代码是这样写的：myspec1=ugarchspec(variance.model=list(model="fGARCH",garchOrder=c(1,1),submodel="GARCH"),mean.model = list(armaOrder = c(1, 0), include.mean = TRUE,regressor=ssecrt),distribution.model = "norm")
myfit1=ugarchfit(myspec1,data=ptfzrt,solver="solnp")其中，外生变量时ssecrt,拟合的数据是ptfzrt
拟合结果是这样的：        Estimate  Std. Error  t value Pr(>|t|)mu      0.002562    0.001299   1.9725 0.048554ar1     0.093450    0.046798   1.9969 0.045837omega   0.000158    0.000073   2.1611 0.030686alpha1  0.118096    0.045725   2.5827 0.009802beta1   0.702471    0.110001   6.3860 0.000000
最后拟合出的garch模型没有外生变量系数这一项的？？Warning message:
unidentified option(s) in mean.model:
regressor




求老师们解释解释