I had the same problem. I fixed it by making sure the extension was placed in the correct directory (extensions/shuffle/UNZIP_HERE). I got confused by the install docs, telling me to unzip in /extensions/ - You have to create a subdir called shuffle, and unzip into that one.
I assume you've activated the extension? I had troubles activating it from Admin pages for some reason, so I had to edit the site.ini.append. Might be worth a check.
Maybe you could edit comment and add info about troubles with activatig this extension from admin panel and your solution? This will be also useful information.