For my master thesis I am trying analyse what are the determinants of Non Performing Loans on a sample of banks taken from the Bankscope database.
I have data for each individual banks for different countries. The, I have added a set of macroeconpomic variables for each country. These variable vary only across countries, i.e. only across bank belonging to different state.
I am not able to report my data here with dataex as when I try to use it, it gives me an error.
Still, my summary statistics show A LOT of variation both within individual bank during the years and across bank, even if in the same country.

When I run FE and POLS, I got EXATCLY the same result with very parsimonious model.
On the other hand, if I run a model with more variables, both and individual levels and macro level, RE and POLS still show the same coefficients but the ui and rho are equal to zero.

WHat I do wrong?