How old and how were the eggs stored before being place into the incubator? Did you purchase these eggs and if so, how were they delivered to you? How old are the parents of these eggs? Where is the incubator itself located? Where in the world are you located? It sounds as if you've been candling them often, which would play havoc on temperature and humidity within the incubator each time it's opened for a few minutes or more, causing delayed hatching or death.
Adding details can help to narrow down the scope of possibilities.
You didn't specify what type of eggs and this website helps with all sorts of fowl and even four legged critters, but I'm going to assume you have chicken eggs. With that assumption in mind, You can expect some pipping and baby chicks in about a week, give or take a few days.
I'll keep you and your feathered family in my thoughts and prayers.