You can definitely get into shows that are listed as sold out. First off, a lot of people book shows and never show up. Just show up 10 minutes before show time and most likely you'll be able to get a seat. Also they will release more seat reservations from time to time, so keep checking the ap. I was just on WOS and ran into the same problem. It was my first cruise, so I assumed that I was out of luck, but that was not the case. You should be fine.