Sometimes the egg whites have a tendency to stick to the non-stick pan making the “flip” difficult if not impossible.
The problem with egg whites is there is no fat, so even in a non-stick pan you need a lot of oil/butter
Buy one quality non-stick pan exclusively for eggs. Also, don’t use this pan for anything else besides eggs
Check if there are scratches in the non-stick surface of your pan. Egg whites are sticking to small bits of food that are burned on the pan.
Coat the pan with either a non-stick spray or olive oil.
Always preheat the pan prior to pouring the egg whites – they will cook better!