Hi rnickerl,
Could you please tell us which browser and OS are you using?
Please check whether you browser and OS support Silverlight from below link which list all supported OS and browsers.
http://www.microsoft.com/getsilverlight/locale/en-us/html/installation-win-SL5.html
If both of them are listed in above table, please check whether your browser has enable Silverlight. For example, in IE, please open Tools -> Manage Add-ons -> All Add-ons. Then find out Silverlight and enable it.
If other type of browser, please feel free to let me know.
Best Regards,
Weiwei