The WP-to-Twitter plugin posts a Twitter status update from your WordPress blog using either the Cli.gs or Bit.ly URL shortening services to provide a link back to your post from Twitter.
Now, I found that there’s a Error message:
There’s been an error shortening your URL! Visit your WP to Twitter settings page to get more information and to clear this error message.
when you enter the plugin options page:
other error reference :http://wordpress.org/support/topic/367742
even you change other url-shorten service,the error exists.
and now the new version 2.1.1 is released and error still exists.
no solution now,if you have know how ,post here. thanks.