The most common problem is confusing inputs with outputs. Anything marked "in" is for accepting a signal from something else. Anything marked "out" is for sending a signal to something else. If you are connecting a cable from the TV's audio input and expecting sound to get to the amp then you're barking up the wrong tree.
Very few TVs have a dedicated audio output on stereo phonos (red & white). Those TVs with a fully wired SCART socket can be connected to a stereo system with the correct cable. If no SCART then you're going to have to rely on the headphone socket.
Don't assume that the Headphone socket volume will change with the TV volume. Sometimes there is an independent volume control from a TV sub-menu. You may even have to enable the headphone socket first, and also disable the TV speakers via menu choices. Check your TV manual.
Once you have a signal from the TV then connect the cable to an input on the amp. The Technics doesn't have an optical input, so it's the red & white phonos you need to use. "TV/DVD in" or "CD in" will do.
Can't give any more help as you haven't said much about how you are trying to connect. This is all just supposition based on the most likely issues. Come back with more detail for further help.