I have a supposedly self fertile pear tree I purchased from BAKKERS 4-5 years ago but it has never even blossomed let alone produced a pear. Tree is healthy enough in every other way. Guess I was sold a dud. Cursed or what. Not a happy chappy.
http://extension.psu.edu/plants/tree-fruit/publications/factsheets/why-is-there-no-fruit-on-my-tree (http://extension.psu.edu/plants/tree-fruit/publications/factsheets/why-is-there-no-fruit-on-my-tree)
The above talks about all the reasons fruit trees won't fruit: too much fertilizer, too little fertilizer, too heavy pruning, too late a frost, etc. I have a cherry tree with same problem. Also it might be the tree is too young yet.