Authorization fail

Hello everyone, I am trying to authorize Adobe digital editions with my adobe ID but it says: The vendor account you entered is not associated with the item you are trying to open. I've already authorized the computer with success but when I try to click on the book and open it, it asks again for authorization, and then it doesn't work. I've tried to de-authorize and authorize it again but doesn't work. Can somebody help me, please? Thank you in advance. Celeste