Tweet button doesn't work in Internet Explorer


Hi everyone,
Instead of tweet button IE (both 9 and 8) render lot of question marks in black boxes and other meaningless characters.
This is my code, which is pasted, so I guess that the error is not there.

<a href="" class="twitter-share-button" data-url="">Tweet</a>
<script>!function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);;js.src="//";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs");</script>

Anybody have idea whats causing this issue? Button is rendering well in all other browsers then IE.
Thanks for you answers!

closed #2

closed #3

closed #4