If the accounting distributions do not match what is in Dynamics 365 then Dooap will let the user know.
User's can manipulate the accounting distribution chart from Dooap itself, but those changes need to reflect in Dynamics 365 as well. This is intended and required to be able to post the invoice.
To correct this issue the user must add the distributions to the PO in Dynamics 365.
Once the user has added the corresponding distributions in Dynamics 365, they may fetch the lines in Dooap which will then show the accounting distributions table up-to-date allowing the invoice to be approved.