Has it flowered?

As you only have one,by the sound of it Guest, it may need a pollinator. Some are self fertile,and others need a bit of friendly company near to you, or in your garden. If you have its name, type it into Google and +pollination and you should get your answer. If in a pot,it might be pot bound, starved, not watered enough. Sometimes you do get a dud too. I have an apple tree in the ground about 5-6 years old and it refuses to perform. Even myself with my years and years of mini orchard growing, may not have a correct pollinator or it's a poor performer anyway.