st: Levpet, program error

["Solorzano Mosquera, Jenniffer" <jenniffers@iadb.org>]

Actually I found it in : www.stata-journal.com/software/sj4-2/st0060/levpet.ado 

But when I try to run it an error pop up:



. levpet lnUSY if panel==3, free(lnUSL) proxy (lnUSM) capital(lnUSK) revenue
no observations
error #2000 occurred in program nllp_bs_gmm
r(196);

Any ideas about the program nllp_bs_gmm?


Jenniffer Solorzano Mosquera
Labor Markets Division - Inter-American Development Bank
Washington, DC - USA
(202) 623-3659


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