Cannot authorise my computer of digital edition 4.5

I have created an adobe ID and have downloaded an overdrive book for our library.  When the digital edition opens after i click on my downloaded book, I am asked to authorise my computer. I am selecting Adobe ID as the ebook vendor and using my adobe user name and password, but I keep getting error message " Incorrect Login ID or password for the selected ebook vendor. Please try again" I have checked that the login and password are correct...Any ideas?