st: mfx after svy: probit - "invalid e(rules) matrix" error

["Erin Strumpf" <erinstrumpf@hotmail.com>]

I'd like to calculate marginal effects after running a svy: probit 
regression, and since dprobit isn't available for survey commands, I'm 
running:

xi: svy, subpop(temp): probit rfullret tx2 i.ragey_e rfemale i.rraceeth 
i.raedcat
mfx

the regression runs fine, but then I get the following error:
invalid e(rules) matrix
r(322);

and the mfx command doesn't run.  I have searched the Stata help files, the 
Stata list, and the internet for this mysterious r(322) error, and I haven't 
come up with anything.  Does anyone have any ideas what is going wrong here?

thanks,
Erin


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