My passion flower vine is quite prolific in producing flowers, however they
never set fruit.

It's about 3 years old, & is quite full. I had a vine with identical
flowers in the past that produced bountiful fruit. There is no indication
of any fruit growing after the flowering ( such as beginning to grow, then
dropping).

Oddly, my Valencia orange tree, about 50' away & in a lower garden flowered,
then did not set fruit. Several other fruit trees are doing just dandy.

Any ideas?

Thanks much!