With the Authorize.Net API if you are setting up a customer payment profile or just setting a billing address you need to make sure the format of the country is set correctly. Here is an example:
$paymentProfile->billToCountry = ‘USA’;
And another variation:
$paymentProfile->billToCountry = ‘United States of America’;
Authorize.net (auth net) will allow multiple formats of country names for billToCountry and shipToCountry
