Fix Key error :Key cannot be the null string

When you get this error message, that mean Barnes & Noble  account info you input isn’t correct,  this is tutorial how to find correct info for a book.

1. Login B&N website, search order history in Barnes & Noble, find order for this book.

2. You will find correct info in order detail,  credit card number is full number, Name is name in billing address of this order.

**if you don’t find billing address in order, that mean it is default address.

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