Should I subscribe to Slacker? Which plan?

[Woodside113]

I just signed up for the premium service on Slacker. The main thing I was hoping to do was the music on demand. From reading these posts it sounds like that is doable however when I try it shows a list of the songs but won't let me play them. I'm using the Sonos controller. I subscribed about an hour ago. Do I need to give it more time or is it something else?