The books will probably be associated with whatever Adobe ID you have registered on the Android where you first bought them.
Double check what that is, and make sure your ADE and Sony Reader are registered with the same Adobe ID.
Some sellers use the Adobe DRM mechanism but with their own ID rather than using the Adobe ID.
In this case, I believe you can make ADE2.0 operate with multiple different ID's from different vendors,
but I am afraid I don't know the details of how to make this work.
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Adobe's ADEPT DRM mechanism and implementation does not understand the concept of user-customer-friendly manner
It must be one of the most user-hostile systems around, even though it is meant to work in for computer illiterate users.
Good luck.