Because Stockbook is a practical program. It will not allow calves to be added if their dams do not already exist.
To avoid this problem, it is best to do two different exports; one for the dams and one for the calves.
When transferring and importing them to the new Stockbook, it is vital that the dams are imported first. So that the parentage exists and are able to match up for when the calves are imported.
Step 1. Export dams
Step 2. Export calves
Step 3. Import dams to other Stockbook
Step 4. Import calves to other Stockbook
Exporting separately will avoid the error that would be received if trying to export all together.
Article ID 4287