The selected game is not currently in progress, or is an invalid game selection. The Tweetcast is for in-progress games only.
With the buttons at the top, you can filter out the updates, choosing to see the ones submitted by TweetCasters for either team, or for both. The default is both.
In the far right column, click on the 'X' to filter out comments from the TweetCaster. For example, you may not find their updates valuable, or perhaps they are inappropriate.