Why are my playlists not allowing me to add songs?

I'm having trouble adding songs. Although sometimes it works, I go to add another song and the box comes up, I select a playlist and click save. Then nothing, it ignores me. I was also unable to create a new playlist. This is really frustrating. I have read the instructions again and didn't find anything. It weird because sometimes it will work and sometimes not, I tried adding a song to each of my playlists in turn and it would only save onto one. ?????