使用stata编写计量中logit progit程序

capture program drop gelogit
program define gelogit
args lnf theta1
replace lnf'=-ln(1+exp(theta1')) if $ML_y1==0
replace lnf'=theta1'-ln(1+exp(`theta1')) if $ML_y1==1
end

ml model lf gelogit (foreign=weight mpg)
ml check
ml search
ml max

这个是写的logit的
报错在.
gelogit work age married children education
==0 invalid name
r(198);
有大佬可以提一下解决方案嘛