Advice needed Propagating Lady Di Pandorea Jasminoides

Hi
I have been trying to propagate Lady Di Panorea from 2 very healthy vigorous plants.
Am using the little propagating greenhouses to maintain moisture. (see photos). Also using peatmoss cups as containers, propagating soil and Yates Plant Cutting Powder. Am following directions for the cuttings.
I do mist the cuttings twice a day to keep the moisture high. They are not in direct sun, but if I set them in direct sun they seem to dry out extremely fast or can seem to "cook". Overall cuttings seem to be fine for about 7 days and then the stems begin to turn black from below the soil up. If left the entire cutting goes black.
I am on my 5th round of cuttings. Have tried younger stems, more older wood cuttings. Cutting at the node, not cutting at the node, root powder with honey, root powder only. All seem to end up the same way.
It is a fast-growing, successful climber so not sure why it is so sensitive to propagate. As another try I have started a new round of cuttings using 50% sand and 50% propagating soil in the container.

I've attached some pics of the set up and of the cuttings. Can I get your advice on what may be causing this to happen? Or is this normal and I should just leave them be?

Any advice or guidance is much appreciated.

Thanks in advance.

heya, i know its a late reply - have you had any success? how did the sand ratio go?
the blackening of the stems is most definitely rot from too much moisture in the soil!

Have you ever tried bending down a winding stem so it touches the ground and burying a portion of it under the soil? i think the technique is called layering. ensure at least one node in under the soil so that the plant hopefully grows some roots from it!