By default, Mac OS X Mavericks / Safari 6.1 and later now load plugins like PDFs, Flash, Silverlight, and Java in a sandbox to protect users from possible exploits in the plugins, but can also prevent those sites from working as designed.
See "Added security for plug-ins" On http://www.apple.com/safari/"PDFs and widely used plug-ins like Adobe Flash Player, Silverlight, QuickTime, and Oracle Java are sandboxed in Safari, which protects your system from harm should those plug-ins be exploited. For added security, you can even choose to run only certain plug-ins on trusted websites you select." For Silverlight enabled sites that do any of the following you may find the sites does not work as expected.Out-Of-Browser installationSaving Files to the local machineMedia Playback, like NetflixLocalMessageSender/ReceiverWebcam
To workaround the problem you can allow Silverlight to run outside the sandbox for the sites you trust.
1. Open Safari to the Silverlight enabled website.
2. Open Safari->Preferences (⌘,).
3. Select the “Security” tab4. Make sure “Allow Plug-ins” checkbox is checked5. Click the “Manage Website Settings…” button
6. Select "Silverlight" in the plug-in list on the left7. Click the pull-down for the Silverlight enabled website and choose "Run in Unsafe Mode"
8. In the Alert, click "Trust"
9. Click the "Done" button10. Close the "Preferences" panel11. Reload the page