st: Need help with ordinal reliability

[Marta Garcia-Granero <mgarciagranero@gmail.com>]

I am working with a translation of the Dyadic Adjustment Scale (Spanier, 
1976) in 915 cases. The scale is formed by 32 (das1...das32) categorical 
items, 30 are 5-point Likert and 2 of them are binary. I have been asked 
to get ordinal alphas for the total score and the 4 subscales (the 
author's got the paper in stand-by until corrected, and came to me for 
help, I have less than two weeks to answer all the questions asked by 
the reviewers) . After searching the Statalist archive I found this 
solution:

http://www.stata.com/statalist/archive/2012-02/msg00696.html

I can't get pass the 3rd line (-factormat- command). I get the following 
error:

factor estimation result not found
r(301);

My code (adapted from the Statalist thread mentioned above):

polychoric das*
matrix define `C' = r(R)
factormat `C', n(915) factors(1)

tempname L Psi
matrix define `L' = e(L)
matrix define `Psi' = e(Psi)

local p = rowsof(`L')

tempname f f2 u2
scalar define `f' = 0
scalar define `f2' = 0
scalar define `u2' = 0
forvalues i = 1/`p' {
scalar define `f' = `f' + `L'[`i', 1]
scalar define `f2' = `f2' + `L'[`i', 1] * `L'[`i', 1]
scalar define `u2' = `u2' + `Psi'[1, `i']
}
scalar define `f' = `f' / `p'
scalar define `f2' = `f2' / `p'
scalar define `u2' = `u2' / `p'

tempname pf2
scalar define `pf2' = `p' * `f' * `f'
scalar define alpha = `p' / (`p' - 1) * ///
(`pf2' - `f2') / (`pf2' + `u2')

display in smcl as text "Ordinal alpha = " as result %06.4f alpha

alpha latent*
alpha das*, std

I'd be very grateful if somebody could help me.

Thanks in advance,
Marta GG
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