"Package 1 has failed validation ... 1021001 No rating rules found for provided combination. Country Not Found." message when mailing to Puerto Rico in SendPro Enterprise
When printing a stamp to Puerto Rico from the Stamps app, after selecting the rate button, the message "Package 1 has failed validation. Error message from PB Shipping API: 1021001 No rating rules found for provided combination. Country Not Found." appears.
First Class Mail International was selected instead of First Class Mail.
Because Puerto Rico is a US Territory, you need to select First Class Mail from the Service menu, not First Class Mail International.
UPDATED: June 19, 2023