有哪位高手能帮我看下程序，以下是split population duration model
stset AGE,failure(TAG)
capture program drop splitpps
program splitpps
version 10.0
args lnf theta1 theta2 theta3
tempvar p s d l
quietly gen double 'l'=exp(-'theta1')
quietly gen double 'd'=exp('theta2')/(1+exp('theta2'))
quietly gen double 's'=1-'d'+'d'*(1/(1+('l'*$ML_y1)^(1/'theta3')))
quietly gen double 'p'=ln('d')-ln('theta3')+((1/'theta3')-1)*ln($ML_y1)+(1/'theta3')*ln('l')-2*ln(1+('l'*$ML_y1)^(1/'theta3'))
quietly replace 'lnf'=$ML_y2*('p')+(1-$ML_y2)*ln('s')
end
ml model lf splitpps (duration:AGE=GENDER JOB SALARY)(logit:TAG=GENDER JOB SALARY)/shape
ml max
我输入后提示我，ml max是invalid name是怎么回事啊？是我程序在哪出问题了吗？错在哪呢，我编的几个ML模型怎么都提示同样的错误，都提示ml max是invalid name呢？高手们，请赐教啊！！！