on IE 9,
when setting the show-count to false, and show screen name to true, the widget appears without the screen name…
<a href="https://twitter.com/koko" class="twitter-follow-button" data-show-count="false" data-show-screen-name="true" data-lang="en">Follow @twitterapi</a>
see this on jsFiddle (open in IE9 and other to compare) :
http://jsfiddle.net/edZKN/9/
