Pervasive error: 1206: Non-db file or corrupted db

Our client has Pastel Partner, uses it for accounting purposes (keeping books).   We integrate with their Pastel in the custom system we've built for them to send out Demand letters (customer's whose accounts in Pastel are in arrears)

One of the features we have in our system is displaying customers from selected books in Pastel for them in the system (we integrate with Pastel and get the customers out Pastel, using the API).  There is one set of books that, when we try to access it, we get the following Pervasive error back: 

-1206: Non-db file or corrupted db
The client says that the specific books became corrupted a month ago, so they removed it completely, cleaned the data up, and added it back into Pastel.   They can access the books fine now in Pastel and the data is cleared/clean, but we get that error still when we try to access those books.    It's only those books that gives us such an error, all the other ones we can access just fine.
Does anyone have any idea of what the issue could be?  Could it be that we should be using a newer version of the SDK file? Meaning the new, clean books they put back into Pastel maybe cannot be read by the older SDK version we have? The SDK details we are using are as follows:
Product Name: SDK for Pastel Accounting Version 7 Beta
Product version: 17.00.0003
Date modified: 2016-10-12
Original Filename: PasSDK.dll
Any assistance/advice would be greatly appreciated!