error message check activation

[Guest]

I am trying to transfer a book from the library to my nook simple touch.  I downloaded ADE 4.5 and was able to transfer the book from the library website to ADE but it would not transfer to my nook.  I called B&N and they stated that my simple touch did not support ADE 4.5 only 2.0 so I uninstalled 4.5 and installed 2.0.  When I then tried to transfer the book from the library to ADE it gives me an error message "check activation." So, I went into ADE 2.0 and clicked "help" authorize computer except it won't let me so I click on check authorization and it shows that my computer is already authorized.  So now what . . . . I can't get the book on ADE 2.0 and although I can get the book on ADE 4.5 I can't get it to my nook simple touch . . . I need help  . . please

[Guest]

FYI . . it also does not provide an option to deauthorize and reauthorize using ADE 2.0 . . I did in fact read other forum answers before posting this!