Thanks for posting your question. There are a few troubleshooting steps you can try:
- Reconfigure your video source via the setup process.
- Verify the provider information is accurate.
- Try viewing on another device to see if the problem is isolated to your Mac.
- Factory reset your Slingbox, and completely reconfigure and set up the unit.
Here is a helpful article that will assist you further in completing those steps:
- Slingbox.com - Channels or lineups missing in SlingPlayer
- Slingbox.com - How to reset your Slingbox to factory settings
Beyond that, the best recommendation is to continue to use the guide directly through your cable-box. I know it's not the best solution, but our built-in guide is provided by Zap2It, which is a third-party provider. There isn't a lot of additional troubleshooting to be done after the aforementioned steps.
Hope this information helps!