Trees refuse to flower for several reasons, but the fact that you have another one flowering means it could be the tree itself and not the lack of sun or nutrients that can also cause a lack of flowers. Has this tree ever bloomed, or just no flowers for the last two years? If the tree is young I would give it a few more years. If the tree is mature and never flowered, it is possible that it is sterile. Add some Osmocote plant food around the base of the tree next spring and if you still get no blooms consider if this tree is worthy of the space in your garden. Life is too short to put up with disappointing plants and there are plenty of other interesting trees happy to grow in your garden. Keep growing, Marianne Binetti