If the TST button on TVGuardian LT mutes and unmutes your TV (or audio receiver), but video content is not muted:
If TVGuardian LT is receiving the closed caption data it needs, the LED light on the front side will blink on and off.
Let's look at the simple fix first. Is the right INPUT selected on TVGuardian LT? If your video source is connected to IN1, the IN1 light should be lighted.
If #1 did not take care of it, check the video resolution settings of your video source. It should be set to 1080i for HD or 480i for SD. If it's set to 720p or 1080p, the closed captions TVGuardian LT needs to read will not be output over the composite video output.
If the TV show or movie still isn't being filtered, make sure you do not have the closed captions displayed on your TV. Some cable/satellite boxes do not output closed captions on the composite video when closed captions are displayed.
Still not working, it could be that the video you're watching does not have closed captions.