Too many people seem to think that training a predator to eat pellets consists of throwing pellets into the tank and then standing there wondering why they aren't immediately eaten. That works with a few fish, but I'd say that many predators species...perhaps even most...require a little thought in presentation.
Get the fish accustomed to eating whatever it is that is currently being accepted. You want it at the point where it hits the target food the instant it is thrown into the water. At that point, try presenting the dry pellet, preferably floating, the same way, when the fish is champing at the bit and expecting another fish or shrimp or whatever.
Plenty of other tricks to try as well. Throwing the pellet into the outflow of a wavemaker to simulate life...dropping in a small handful of what it likes mixed in with the pellets you want it to like...switching it over from live prey to freshly killed or frozen versions that are stuffed with pellets and increasing the percentage of dry food over time...accustoming the fish to eagerly taking food from forceps, and then swapping over to pellets...you need to use some imagination and some ingenuity. If you have a big pike cichlid...it's got a brain that might be approaching the size of a small pea. Outsmart it.