I had the same promblem until I went to the grower who has a huge 18 footer in his greenhouse and asked him the same question.
These trees or plants will only bloom and smell unbeleivable if you let them grow in COLD conditions for a period of time. His does not bloom all year until fall and winter. It is in a greenhouse that is kept in the 40's to 50's all winter, and boy is that tree loaded with flowers at that only time. Sometimes the flowers will appear out of no where if the morning in cold enough for them to come out!
I tried it. I have 3 of them. One of which I left out in a cold room with sunlight, one I left outside under shrubs so frost wouldn't get to it, and one I brought indoors into my warm sun room.
The one outside grew tons of flowers and lasted until the end of October, until it was to cold to keep it outside.
The one in my cold shed flowered throughout the whole of winter. The one indoors, nothing. Just constant new growth.
Given warm temps, they only grow leaves, and as soon as the warm sun hits the plants after a cool morning when I get flowers, they frizzle up and die. Try it. Leave your plants growing in cold conitions for a while. Do not over water, and don't fertilze ok.
They do not like fertilizer like most plants. In fact the grower never feeds his.
I hope this helps. I have great sucess with this plant!! They have the most fragrant yet suttle scent!!!
Remeber, because you are going to keep in in cooler temps, back off on the watering ok.
Mike

Great suggestions. The tree is in full sun planted outdoors, I get great growth and it has beautiful leaves. I'm in NC so it goes through the whole winter outside, and I've actually only fertilized it once when I planted it. I was also told that it was better left alone, so thats what i've done. Thanks for the help. Maybe this fall will be the lucky one!

Remember,
your tree has to get at least a few weeks of contiual cold. I promise it will flower for you. Too bad you couldn't put the plant it in part sun, because I know your sun there is too hot to have the flowers last past the am if you ever get flowers..I hope it all goes well. let me know ok...Mike

mike,
these will take some frost. they can be tender in zone 7, considered hardy in zone 8. an extended hard freeze of several days will damage the shrub.
the flowers also last more than one day and sun won't kill those as it should begin flowering in the fall when the weather cools.
kwander,
are you pruning your shrub? the flowers form on old wood and pruning will reduce flowering.

jeff-
I haven't done anything with it at all. No pruning, no fertilizer except the one time, no nothing. Its mulched and continues to sprout great new leaves, but just no flowers. Its about 75 degrees right now and I just went to look around the corner, neighbors are blooming out of control even in this warm fall weather! Maybe mine just needs that cool weather for a kickstart. thanks

Will these shrubs set flowers in winter in central florida?