Thank you for using our answers forum! I'm sorry to hear you are having trouble connecting to your Slingbox remotely. However, the message you are getting is from your Cable Provider. The Cable Box may be disconnected or not working for some reason. The Slingbox just relays the message through the Slingbox because that's what it is getting for video. If you were to actually watch the Cable Box at home, it will give you the same message. If you contact your Cable Provider, they should be able to resolve this issue for you. Feel free to reply if there are any further issues.
Hope this helps!
The Sling Moderation Team