SlingPlayer for Chromecast was designed to only work with an iPhone, iPad, and/or Android Phone SlingPlayer applications. Have a look at the following article for more details:
If you would like to see this work on a laptop, you will have to make an Enhancement Request at the following link below:
Hope this helps!!!
Sling Media Moderation Team
Sling player apps will not work eith chromecast for the past number of weeks , several users receiving the "unable to connect (2)" error. This has nothing to do with portforwarding or deleting/reinstalling an app
It would be nice if a sling rep could advise on this issue as it has been ignored in several threads