Always Invalid country code when trying to get rates

[Stelikas]

I'm trying to grab VAT rates for specific countries but i always get the error:

Invalid country code "country"

What i'm doing:

     $rates = new Rates($_SERVER["DOCUMENT_ROOT"].'assets/vat.txt');
     $rate = $rates->getRateForCountry('NL'); // 21
     return $rate;

[Stelikas]

That error happened because i had already created the txt file manually.