Smart playlists won't update, remains empty even after weeks

Before I updated to the new iTunes, my smart playlists worked fine. My current version (11.0.3.) does not seem to add songs to or update any of the playlists I have created since downloading the new version. I have turned my itunes on and off several times and the version is up to date. I read this thread, posted by someone who had the same problem but his/her playlist automatically updated itself a few hours after it was created. Some of my smart playlists have remained empty for weeks. How do I solve this issue? It is driving me crazy.