It is possible that the remainder of the ship was booked up by a group, and still have your booking in place. It would not necessarily bump out your booking. You would just be cruising with a large group onboard. ... The other possibility is that the ship might be going into dry dock for your week. That happened to us once. One week our sailing had lots of room available, next it disappeared from the listings. Our TA asked the cruise line what was up, but was led to believe all was fine. She was still suspicious that there was a dry dock planned. We just waited it out, and about two weeks later the dry dock was announced. The cruise line did make us a nice offer to compensate for our inconvenience.