Dahlia propagation

I took my first batch of Dahlia cuttings last week. They look OK, indoors in an unheated closed propagator. I've never succeeded before, maybe this year...
I will probably be able to take another batch this week but I feel I started a bit late in the season so after that I will pot up the tubers.

I dont think its too late.... I took cuttings into May last year and they still flowered. 
I would love to know how you get on. Every time I used a closed lid on my propagator they died off from "black leg" 
I see people taking the cuttings by 100s and would love to crack it.