I was reading this thread:
Sony eBook Library software: should I install? and another thought occurred to me that should probably also go into the Guide:
For ADE to connect with the Sony Reader (any of them) you must have installed the Sony EBL software, even if you don't use it. The reason is that ADE uses a Sony driver that is installed during the EBL installation. If the driver is not present, ADE will not see any Sony Readers.