Thanks for posting in the forums! I apologize for the inconvenience of not being able to control your A/V source via WD TV. I have posted a link to an article from our support site that may help troubleshoot this issue.
Here is the link:
Have a great day!
The Sling Moderation Team
that link would be helpful if you could actually use the things that are greyed out..
I have same issue, I'm using a ProHD and WDTV live and can't change channels.
I think the problem is because I have cable coax (no box) going straight into slingbox,and when I do the setup,it gives me a generic remote for online use.