Dashboards Module versions 4.1.2-4.2 : Microsoft Silverlight is Required for Visualizations to Display
In order to display Visualizations on the Dashboards Visualization islands, Microsoft Silverlight must be installed on the machine. Microsoft Silverlight is a powerful tool for creating and delivering rich Internet applications and media experiences on the Web. Silverlight must be installed on each client machine that wishes to display the Dashboard Visualizations within the Passageways Portal.
Please see the Microsoft KB for more information regarding Microsoft Silverlight.