sorry about the mis-idenetification.
your issue is exactly what AJ has said. you can't transfer ADE books that way you have to use ADE to transfer them
Here are screen shots to show how it should look in ADE. The device appears in the column at left. the books on the right. you drag the book to the device to transfer. If the device doesnt show there its not recognized by ADE and wont ask you to authorize it. That means the device doesnt support ADE DRM.
From the specs on the Dick Smith site I would say it doesnt because it doesnt list DRM protected EPub as a supported format.