You need to connect the yellow video outputs from your signal sources only for filtering profanity. Those connections are not necessary for doing the muting test.
When you press the LRN/TST button for the muting test, be sure you don't hold down the button because if you do, then the IN1 light will start blinking, indicating the TVGuardian has gone into the learning mode.
After you have identified the area of the IR sensor on your TV, usually indicated by a tiny light behind a rectangular or oval plastic area outside the TV screen area, you must put the black IR bulb flat against the area when doing the muting test. Also, you may have to move the IR slightly a few times over the area to find the right spot for muting.
If you have moved the IR bulb over the entire IR sensor area without being able to mute the TV, then try the optional procedure at the bottom of the instruction card for teaching the dual muting code.