If you have not already done so, please ensure the information required for a domestic parcel shipment is entered. See here for more details: Ship a Parcel
International shipments in SHIPSTORE are fairly straightforward in terms of what data they need. Any international paperwork needed for a shipment can either be generated in PDF form or sent electronically to the carrier if they accept this data feed.
International Shipment Field Requirements
For information on more advanced settings like submitting data electronically and AES filings, see here: International Options