could also be the service that's trying to be used. USPS has puerto rico
set as a state and US as the country code. UPS/FEDEX and DHL have it set
as PR as state and country code.
Have you tried verifying that all the information is correct? Are you
using google chrome as a browser? If yes to both questions above, clear
cookies and cache and try doing this in an incognito window and see if
that works. If this does not work you...