Tango Twirl, didn't

I've grown Tango Twirl since it came out a few years ago. This year, the plants I wintered over in my garage, came back just fine. Until it was time for the buds to start to grow. That is, it set a lot of buds... but then the plant started to wither and finally died. What did I do wrong? I had it in sun, raised in a pot, watered but not wet, with diamond frost euphorbia to keep it's feet shaded. I'm stumped!

I'm also curious about Tango Twirl. Mandevillas grow like crazy down here and mine are beautiful! I haven't seen any Tango Twirl here though. Probably I can get one through the market. However, they are pretty inexpensive here and when I order things, the shipping costs can be prohibitive.

I am able to leave mine out all year, except when we expect a hard freeze, I'll cover them with a sheet or something. I have a number of Mini Sun Crimson Parasol and they are very pretty. I also have the reguar Sun Crimson and they are beautiful growing through the balusters on my porch!

Kaye C