Finding more about what exactly went wrong when processing your shipments is very easy using the warning signs in the Shipments section. If you get an exclamation mark or a dark circle next to a shipment, simply hover over it and a small pop-up window will come up and let you know what exactly went wrong with your shipment:
Warning sign:
Dark circle:
Warnings will display a green checkmark for generating the shipping label, but red exclamation marks and dark circles for any or both of the remaining areas.