Thank you for posting on the answer forums. With the information you are providing me it sounds like an issue on the cable box its self. What you can check is if you go into the audio settings on the cable box there should be an optimize or volume settings. Sometimes when connecting the HDMI in the cable box turns off other outputs (component) and makes it impossible to get audio even when running the cables to your TV. You can contact the cable component if you can not find the setting on the cable box to turn on the audio.
Hope this helps,
Sling Media Tech Support