I am hoping someone can help with this, I am using the following code with a hospital administrative dataset with rare events:
teffects ipwra (readmission alter sex i.charlindex i.imddecile) (ind alter sex i.charlindex i.imddecile i.n_hrg3, probit) , atet

and I keep getting the following result:

missing values encountered in analytic gradient
gmm estimation failed

The covariates are coded in a manner whereby there aren't missing values, so I am not sure what STATA means by "missing values encountered in analytic gradient"?