If your engine is dark and silent when you apply power then that means one of two things:
1) There is no power to that section of track. That is unlikely since it is the track section with the power lockon. You can eliminate this possibility by testing that section with a lighted caboose.
2) The engine is receiving the DCS signal (which is why is stays dark and silent) but the signal is not good enough to add it to the remote.
Here are a couple of easy things you can try after you eliminate #1 as the problem. First check the track to make sure it is clean. Next check the engine wheels and pickup rollers to make sure they are clean. You can also try moving the engine to a different spot on the layout.
You should be using "Add MTH Engine" when you are trying to add it to the remote. The "Add TMCC Engine" command won't work for an engine from MTH.