http://imgur.com/a/xg6lB

Hello Everyone, so I bought this Plumeria Cutting at Epcot during the flower and garden festival, and it doesn't seem to be growing recently. The buds on top have unfurled and gotten much bigger but they haven't changed for maybe 3 weeks. They're a dark purple, almost black color, but they're still flexible and plump. It should have taken root by now but still feels very loose in the soil. I'm not sure what's wrong? More info below

I bought it the last week of May and planted it the first week in June. It's planted in cactus mix potting soil, with some gravel in the bottom.

It gets about 5-6 hours of direct sunlight a day, when it's not raining, in temperatures of about 70-90 F. Per what the seller told me, I've watered it twice, once 3 weeks after planting, and once 2 weeks following that, both times with just half a cup of water.

Is there something wrong with it or my care of it? Does it have black fungus, or another disease? Any ideas?

Thanks in advance!