Levpet r(2000)

Hello,

I am using the levpet command on a subsample of my observations (specific sector and year). Here is the code I am executing:

levpet ln_real_VA if NACESHORT==10 & year==2005, free(ln_L) proxy(ln_real_M) capital(ln_real_K) reps(20) level(99)

Unfortunately, Stata keeps sending me back this error message:

"no observations
r(2000);"

The error remains even if I change year or sector.
If I instead use revenues I get a different, yet very similar message.


. levpet ln_real_T if NACESHORT==10 & year==2005, free(ln_L) proxy(ln_real_M) capital(ln_real_
> K) reps(20) level(99) revenue
no observations
error #2000 occurred in program nllp_bs_gmm
r(196);

I am fairly sure there are observation for the subsample since:

count if !missing( ln_real_K, ln_real_M, ln_real_T, ln_real_VA, ln_L) & NACESHORT==10 & year
> ==2005
1167

Where I am getting this wrong?

Thank you for your help,

Luca