De-authorized devices.

Can someone please help me. Adobe support sends me to this page.

I need to have an old PC de-authorized as well as a HP Probook laptop. The laptop has been de-authorized via Adobe Digital Editions, but I'm afraid I forgot to do that on the old PC: I should be able to at least use the authorization that was on the laptop that has been de-authorized, but I receive this error when trying to authorize another device:

You can only authorize this computer with an Adobe ID that hasn' t been previously used to authorize any other computer or mobile devices.