I have created my first playlist today. I've got about 100 tracks so wanted to start organising them. Now I've created a playlist I want to add more tracks to it. However, this function doesn't seem to be available to me. When I go to one of my own tracks, click "more" then click "add to playlist" it opens a new window. In the walk-through on the help section it shows the new window having 2 tabs (one says "add to playlist" and one says "create new"). When I try, the only option available is "create new", which means I can't select an existing playlist to add the track to. Can anyone help? Is there something I'm doing wrong?