Have you authorized the eReader with the same ID as your copy of ADE?
Under ADE2.0, menu~Help~Authorize Device
Under ADE1.7.20, in Library view, menu~Library~Authorize Device
I,m not sure how you do this.I never had to do this with my other computer
To make it work, you need the computer and the device authorized with the same AdobeID.
This must be an explict AdobeID, not an 'authorize computer without ID'.
Maybe you registered the old computer with your AdobeID, and the device from that?
And maybe with the new computer you have not yet registered your AdobeID?
Assuming you are on ADE2.0, check that with ctrl-shift-I to ADE (cmd-shift-I on Mac).
That will tell you the ID you are registered with.
If the new computer isn't registered with your ID,
- crtl-shift-D to ADE to remove any trash registration it may have
- restart ADE
- Register ADE with your AdobeID (ctrl-shift-U)