The Invoice and Purchase items need to be set up in a specific way in order to ensure that the invoices will post across to your external accounting system successfully.
If your invoice won't post through, it could be for a variety of reasons.
One of the main reasons however is the items need to be perfect. If you are using the pre-configures invoice and purchase items from Wise Owl, they will work fine.
If you create your own, you may get errors such as the example below.
Item 'xxx' (xx) has not been successfully imported for this invoice
If you get this error, please ensure that:
There are no duplicated names or codes in your invoice and purchase items
Check that your invoice items account code is going to an income account
Check that your purchase items account code is going to an expense account
Once you have checked your items are matching suitably, resolve the error and re-confirm the invoice to post it across.