iMac doesn't recognize My Book

When trying to download updates to My Book, I get a message basically indicating that My Book is not connected to my iMac. But it is! and Time Machine backs up to it, and all my connections are tight. What is the problem? (PS/I bought My Book is 2007 and the extended warranty expired in 2010 - but I was not warned about the expiration, so did not extend it.)

If the drive is working OK don’t bother with the firmware updates. If it ain’t broke don’t fix it.