Thanks for posting in the forums! I'm sorry to hear you are unable to connect via WDTV. If it's saying you firmware is not up to date, I would recommend going to support.slingbox.com. If you are logged into your account, the home page will display your Slingbox information, including it's current firmware version.
Below is a link to an article from our support site that explains how to get the latest firmware version and what the latest firmware version for each model is:
Hope this helps!
The Sling Moderation Team