st: Capture failing on xtmixed

["Adrian Sayers" <adrian.sayers@bristol.ac.uk>]

Hi,

Apologies for posting this again.

I have come across some odd behaviour.

I am attempting to capture xtmixed in a simulation study. However it doesn't
seem to be working properly

So i have :
capture noisily xtmixed     obs_ht  age_1 age_2 || id: age_1 age_2 ,
cov(unstruct)

it has trouble converging. And eventually gives the following error:
	
	Hessian is not negative semidefinite
	conformability error

and then stata exits (Aborts) the program.

I am not sure why it is just not being skipped, and the error code stored in
_rc as it should be. 

I have a feeling it is to do with some of the mata code.

Any ideas or suggestions for a work around or a proper fix would be greatly
appreciated.

I am running stata 12.1

Thanks

Adrian



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