You may encounter the error "Insurance is not available with this service/packaging combo" when trying to add insurance to a USPS shipment that does not include some form of delivery confirmation.
Most USPS shipments (domestic and international) can be insured in $100 increments with Shipsurance. However, Shipsurance insurance is only available when a form of delivery confirmation is on the shipment (i.e. tracking, delivery confirmation, signature confirmation, adult signature confirmation).
To add insurance to a shipment, you will need to select a service that includes delivery confirmation or add delivery confirmation to the shipment. You can add a Confirmation option on the READY TO SHIP page, from the "Additional Shipment Options" Confirmation drop down menu.
Learn more about USPS Delivery Confirmation, including which domestic services include it, and find out more information about tracking USPS international shipments.
How to: Insure a package
How to: Add full insurance coverage to all orders over a minimum value
What USPS services include insurance coverage and offer additional insurance?
What is the cost of Shipsurance for a shipment that already has included insurance?
How to: Find out how much Shipsurance coverage was purchased for a shipment