If you are hatching them upright the fat end must be up at all times. Instead of turning the eggs then, they should be tilted through a 90* angle from side to side, 45* over to one side, then after a few hours 45* in the opposite direction. If you are laying them flat on their sides, they should be turned, like the above poster described. Mark them with an X and an O and turn them an odd number of times per day, say the X is on top, turn them so the O (on the opposite side of the egg) is on top.
Incorrect turning of the eggs does have an effect on the hatch rates, but things like humidity, temperature, age of the eggs before setting, whether or not they were shipped eggs, handling of the eggs prior to and during incubation, as well as the age, health and diet of the breeder flock all plays a part. If you can give us more details we may be able to help you figure out what the problem is.