st: how can I pass a parameter to gengammareg?

[Matteo Richiardi <matteo.richiardi@gmail.com>]

I'm trying to use the gengammareg ado file within the minbound
command, but although everything seems working (separately), the
program doesn't work.
This is what I have written:

********************************
capture program drop simulation
program simulation, rclass
       version 10
      args s
       capture drop t_sim
       gengammareg t_sim, kappa(1) sigma(`s')
       // stset the data and fit a Weibull regression model
       stset t_sim
       streg, distribution(weibull)
       scalar s_hat_sim = r(est)
       return scalar diff = s_hat_sim - .5
end

// MINIMIZATION
minbound simulation, range(.01 1) trace

********************************

And this is what I get from Stata:

failure running quadratic on x =          .01

It seems as gengammareg accepts parameters only manually. Any idea on
how I can get round of this problem? Thanks so much for support,

Matteo

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