This can occur if you purchase an ebook package. The package contains more than one ebook, so once the purchase is complete each individual ebook in the package is added to your eBooks.com account.
But sometimes there is an issue with adding the ebooks to your account. If you are downloading to Adobe Digital Editions (ADE) or the Ebook Reader app then the error message displayed can be the same one used for other issues. To test this is the issue please try to open your ebook in the online reader.
A popular ebook package is the Science of Happiness Package. If you are not sure if this is the issue you are encountering, here is an example of the error message shown in the online reader:
The Science of Happiness Package
Thank you for purchasing The Science of Happiness Package.
If you are seeing this book then a problem has occurred associating Born To Be Good
and The Compassion Instinct with your eBooks.com account.
Please contact eBooks.com Support with your invoice number for assistance.
If you encounter the error please do not worry. Simply contact our support team stating you bought an ebook package and the books have not been added to your account. We will add the ebooks to your account and let you know they are ready for you to read them.