Hi, everyone! I am an undergraduate student who is researching for his thesis about international trade. I am estimating a gravity model about non-tariff measures. I am using ppml estimator for this purpose, but I have some problems with it. I'm estimating a cross-sectional gravity equation for a sample of 50 countries and 21 HS sectors (260 000 observations) with fixed effects for each of them (country-specific and sector), but when I'm running my regression, the PPML method doesn't give me a result table (it doesn't find a max. valor after 100 iterations). I was wondering if the problem is the high level of fixed effects, so maybe i should tried the ppmlhdfe estimator, but i'm no sure. Any idea about what is happening with my model?
I attach my regression code.

ppml exportaciones lnPBI_partner lnPBI_reporter lnDistancia frontera lenguaje colonia ALC mediterraneo arancel_NMF MNA_dummy exp_dum_* imp_dum_* seccion_dum_*, cluster(distancia)