Plastic combs won't get the eggs out. You need a metal comb. Kp24 has one, but you can get others. At woollies there's one with a long yellow handle.
The prongs on these combs touch each other, so they will get the eggs off the hair. Even after that always check & get any remaining eggs off with your nails.
Freshly hatched lice are tiny & impossible to get with a comb. They sit right on the scalp & are really hard to see if you're not looking close enough. They just look like grains of sand. They also avoid treatments if not rubbed right into the scalp.
Cheap conditioner is the best thing to comb with.