what version of internet explorer are you using? edge animate (html 5) is not supported in older versions of internet explorer.
you can test your browser's html 5 performance here: http://html5test.com/index.html
this is from their FAQ:
Has the output from Edge Animate proven to perform well on devices and desktop browsers?
Yes, the animated content created with Edge Animate is designed and tested to work reliably on iOS (iPhone and iPad) and most Android devices. The Edge Animate stage utilizes WebKit, which means animated content is created on a true browser surface for consistency on WebKit-enabled devices. Also, content produced with Edge Animate has been tested on popular desktop browsers like Firefox, Chrome, Safari, and Internet Explorer 9. For older, non-HTML5 browsers such as Internet Explorer 6, 7, and 8, Edge Animate has a down-level stage to create fallback versions of your projects.