downloading an epub book to my ipad and keep getting the error "Invalid Title"

[Guest]

I am tyring to download and epub book from my library to my ipad and I keep getting the error "Invalid Title-This application is not currently authorized to open the book.  Please verify your Adobe Id and try again.  When I sign in with my Adobe ID, I get the message that the authorization is successful, but when I go back and try to download again, I get the Invalid Title error again.  How anyone else had this problem?

[sjpt]

Which app are you using on ipad.

I find Bluefire the most reliable.