Do you have dry skin? Mine is rather dry, and I get nowhere near the longevity that my friend, who has oily skin, does. It lasts longer than a half hour, though.
If dry skin is the case, then applying some unscented oil (jojoba works well) or lotion before applying fragrance can help.
Also, I'm not sure when you apply your fragrance. For longevity, it's best to apply right before leaving the house, as opposed to right after a shower or bath.
Finally, here's a recent thread on a similar question, with some good answers: http://community.basenotes.net/showthread.php?t=235458