American Passion Flower, When to Harvest

I bought a pack of seed of American passion flower (S4440-100) in 2003, and sowed it last October. The plant itself is growing very well, and it has flowers and fruits now. However, when I cut the green fruit in half I found that it's empty but with two rows of seeds only. Am I growing it wrongly, or does the plant itself have a defect, or it will have fruit when it turns yellow / mature? Would you please see attached pictures for details?

The pictures show a plant that is growing very well and you certainly are not growing it incorrectly. The fruit looked green and immature. Wait until they turn yellow before harvesting them.