[delphin]

On Mac's the Sony Reader Library will recognize the Sony Readers where ADE will usually not recognize them.

If you can see the book in ADE, then it was successfully encrypted to match your master Adobe ADE DRM Key, so you just need to ALSO get your Sony Reader Library keyed to the same DRM authorization key.

To do this, as already suggested, just open your Sony Reader Library and authorize (or reauthorize) using the "Use Existing Adobe Authorization" option.

Then you should be able to import the book into your Sony Reader Library Software from your ADE "My Digital Editons" folder and then drag it onto your reader.

In the future, for simplicity, you can just download purchased books directly into your Sony Reader Library, instead of using ADE.