the vendor account you entered is not associated with the item you are trying to open

Error :"the vendor account is not associated with the item I am trying to open" comes when you are trying to open a book but current ADE authorization is different from the ADE authorization that was used at the time of book download.

Solution:

1. Click on the book.

2. You will get a prompt "Computer Authorization needed"

3. Click on "Continue"

4.Enter the credentials that was used at the time of book download.

5. Click Authorize.

Now you should be able to open your existing books

"Enter the credentials that was used at the time of book download.5. Click Authorize."...

I paid for and downloaded the book over a year ago from Kobo. I used the same password (the same as my Adobe password) and it does not work. I reinstalled (and deleted Adobe>adept from the registry). Still doesn't work. I cannot download it from Kobo since it says it is registered to "another name" (probably an old password on my old computer?). I REALLY need to be able to use this book that I paid good money for in order to to quote some passages for a museum installation. Now thanks to some convoluted Adobe vendor ID protocol, I cannot use this book and have wasted all afternoon trying to figure out how to find these passages in my book. 

...updated a day later...I did eventually find and downloaded the Kobo for desktop app/program which worked. However I cannot copy and paste passages. I need to do a screen grab from the Kobo page and then use OCR software, and then edit.