Thanks for posting to the forums.
Because you did change cable providers, you would have to reconfigure the current input of your Slingbox to your new cable provider. The following article will help you configure your Slingbox for a new cable box:
I would also make sure the External IR Blaster is connected to the Slingbox and the pyramid part in front of your cable box about 2 inches. This should let you control you cable box again.
The following article details troubleshooting for your External IR Blaster and an image of what it looks like:
Hope this helps !!
Sling Media Moderation Team