When creating a 'New Shipment' on the actions bar in Shiptheory you might get the error: 

''Unable to create label Error confirming shipment: Invalid number of products. (128039)''

To resolve this, you need to go to the section that says 'Specify Shipment Contents'.

You need to tick the box and enter SKU, Product Name, Value and Quantity.

If you are still having issues after adding your product, please contact support, and we'll be happy to help.