Thank you for posting in our answers forum! I'm sorry to hear you are having an issue with Watch on Slingbox.com. However, could you take a look at this article below and tell me if this fixes the issue for you? If not, it may be an issue with the plug-in and Internet Explorer. In that case, I would recommend trying another web browser, such as Google Chrome or Mozilla Firefox.
Hope this helps!
The Sling Moderation Team