Hi AnneMarie, have you tried the knowledgebase's suggestions to your error?  The Knowledgebase can be found on Resources, Solve, Search Knowledgebase.  Type the error in the search field & there are over 4 articles dealing with the error.

Hi Andrew - I have yes, and in the articles the answers refer to a document but the document being referred too on the KB is no longer visible/available

please provide the kb number you looked at and also more information about the error especially at what point do you get the error.

KB ID 16941 and 67991 - on the manual matching screen - select items (lines go to green) Click Matching and then receive the error "due date being paid error" on specific invoice