st: permute xtmixed

[Fotios Drenos <rmhafdr@ucl.ac.uk>]

Dear All,
I am trying to run a permutation tests on an xtmixed command and the 
I get a convergence error.

The command I am using is:

program test5, rclass
	version 9
	args dependent fac_gene fac_measurement
	xi: xtmixed `dependent' i.`fac_gene' `fac_measurement'||sno: 
`fac_measurement', cov(unstruct)
	testparm _I`fac_gene'*
	return scalar pgene=r(p)
end


permute sqrtchol t=r(pgene), reps(100) noi : test5 sqrtchol gv242 visit

Any suggestions of what goes wrong here?

All the best

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