Welcome, Ann!
I take it that the berries are falling off before they turn red? Lack of water is the most common cause of that, though that's difficult for a plant as deep rooted as a Pyracantha. Is it maybe in a pot, or in a very hot, dry climate, such as eastern California, southern Arizona, New Mexico, or west Texas? Another thing that can do it is lack of pollination, if bees are in short supply, but that usually knocks them off within a week or two of flowering. If they are falling off after they turn red, that may just be the nature of the kind of Pyracantha you have--'Victory has an annoying habit of dropping its berries shortly before Christmas, here.