Yea, like Roberta, I've gotten a number of Ctsm from South America and they always took over a year to get on our summer/winter schedule. Going leafless during the summer, full on growth time, is what prompted the question about a possible import.
Import or not, you can't really force it...give it warmth and it will eventually sprout new growth. FWIW - I would not keep it in the dark. Set it in a warm, bright spot and that might speed up the process.