本人初学stata,照教程写的以下关于MLE的程序不知道哪有问题,请大虾指点~~感激不尽

. capt prog drop bb
. prog define bb
  1. args Inf u v
  2. quietly replace 'inf'=-0.5*ln(2*_pi)-ln('v')-0.5*($ ML_y1-'u')^2/('v')^2
  3. end
. drawnorm x,n(100)m(10)sd(3)
(obs 100)
. ml model if bb(x=) (variance:)
"bb(x=)" invalid evaluation-program name
r(198);