st: Re: xtprobit and missing s.e.

["jyotsna puri" <pjyotsna@hotmail.com>]

Hi all,

[I have looked up previous postings on this, but found that
although they helped me in some things, they don't
help to answer my ultimate question.]

Quick summary: I run an -xtprobit- and get missing s.e. for
Lnsig2u, sigma_u and rho. I run -vce- and get a full matrix
of variance/covariances. For lnsig2u, I get 0s in
all columns.

I am keen to understand what this means.