You will receive this error if you have not physically printed off the Invoices in Pay & Bill. So in the first instance you will need to print those off.
Go into Pay & Bill
Invoicing
Invoice Print
Print Invoices
Then Go into Safe Financials
System Admin
Interfaces
External Interface Controls
Locate the Batch
Right Click Validate
Then Right Click and Post
If the above does not resolve the issue for you, please contact us, reference the title of this article and please include details of the batch, a screenshot of the error message and details of an example document that is not being imported.