Thanks for using the answers forums! I apologize for the inconvenience of not being able to connect to your Slingbox via Surface RT. The desktop SlingPlayer you are using is no longer supported. Have you tried connecting to the Slingbox via newwatch.slingbox.com, at all?
The surface RT is a tablet, with that being said, we cannot gaurantee that it will work with our web applications. In order to stream from any mobile device, you would need an application for that device, which we do not yet have for Surface RT.
Feel free to reply!
The Sling Moderation Team
It works for SOME slingboxes with this address to invoke the embedded version of slingplayer: http://slingplayer.slingbox.com/embedded/slingplayer.php
But I have an older slingbox (the Slingbox PRO), which is not compatible with this embedded player.
It has been almost (over?) a year since I got my Surface RT, and I still cannot watch my slingbox content on it.... this is very sad..