Did it eat yet?
Yeah, pellets are the toughest. I still can't get mine to eat pellets even though the ray eats pellets and I still offer it everyday. Mine would not eat bloodworms. I'm ok with them eating frozen shrimp and smelts for now.
If your fish is eating frozen, you can try this method.
You can feed it raw shrimps (make sure the mouth is large enough to swallow and it doesn't choke), cut open the shrimp and fill it with pellets. Also, make sure your NTT does not have an allergic reaction to shrimps. In my past experiences, I found some tigers get an allergic reaction after ingesting shrimps (pop eye). Use white shrimps and not tiger shrimps / prawns (tiger shrimps have enzymes deficiency like gold fish which cause HITH disease). At first it might split it all out, but most of the time it will swallow together (I used massivore pellets). After a few months, it should be able to eat pellet by it self.
If the whole shrimp is too large, cut it smaller and same goes for the pellet!