How large is your LSN? When my TSN was small I fed him earth worms. They interested him because they were alive and wiggling. From there its fairly easy.
Seriously, getting your fish off live will help you tremendously.
If your LSN is healthy, I would try starving for a bit. Or try feeding at the same time every day, from the same side of the tank, etc. When he gets excited for the fish to be dropped into the tank and paying attention to the same area...drop in a dead fish instead of a live one. He'll most likely nail it. Do that for a bit, then try frozen silversides, shrimp, tilapia, etc.
My TSN took more work to get on pellets than my RTC, but he learned quickly after he picked up a few pellets while he was chewing on raw shrimp.