Joomla - Addthis - Tweet icon problem

Hi, For one of my websites we have a problem with the Twitter icon (generated through Addthis). The (Joomla) website is a blog, you can navigate using the pagination at the bottom. You can navigate through 10 pages. On the first page untill +/- page 8 the tweet icon is displayed correctly. However in Internet Explorer on page 9 + 10, the icon styling is gone and only the link is visible. In Firefox everything is displayed correctly. Who can fix this small issue? Url on request. Thanks!