I see that you are having issues controlling your new AV source with the Slingbox. Since you changed your TV provider from DirecTV to Comcast, you must configure the input and enter the information of your new AV source on the Setup Assistant so you can control it.
Feel free to use the following link to retrieve the instructions:
Take a look at this article. It'll walk you through everything you need to do to reconfigure your virtual remote to match your Comcast box:
Hope this helps!