Why can't I vote on iTunes Radio songs? The like and dislike options are grayed out. I'm on an iPhone 5s and iOS 7.0.

Any ideas?
According the Apple support doc for iTunes Radio:


  There may be some DJ-curated stations that you may not be able to
  modify. You can't like or play more tracks like this while listening
  to some DJ-curated stations. You can however, start new stations based
  on the current track or artist of a featured station or add tracks to
  your iTunes Wishlist from the Star (✭) menu.