A lot of people seem to have trouble with this otherwise desirable group; in this mild maritime situation we have canopy shelter, temps mostly under 30C during summer and cooler nights. So if you can modify your situation in this direction with shelter and shade, you might have success with flowering and general health.
This vine is supposedly hardy down to a soft Zone 8. Its leaves are tender and spinachy though, so I wouldn't put it anywhere it cops wind, hail or more than a brief powder frost. This one is potted and spending some time outside during winter to kill off the bugs that had scuttled over from a manky Hibiscus I'd put on a nearby windowsill. Other than this minor issue, it's never given me any trouble, self-twining over a 6 foot bamboo tripod in one season even with a couple of major hack-backs. The flower cover in these pics is relatively sparse compared to its usual performance as I had unfortunately hosed most of them off getting rid of the aphids. The bellbirds are hanging around it already, looking for nectar. I highly recommend this plant if you can find one.