I had a major problem with clones for a while. I was around 30% success rate.
I didnt change much, but I am something like 100% since I made the changes.
Soak rockwool in a mixture of 1ml clonex jell, 2.5ml Formulex per 1000ml of ph'd water for 24 hours.
Make sure donor has been watered within the last hour.
Clean scissors to be used with rubbing alcohol.
Take cutting (fresh growth only, no old branches)
Recut 45deg cut under ph'd water with a drop of rooting jell in it.
Trim off tips of any fan leaves. I think this is the important bit, when I didnt do this, they all took forever to root. By clipping the tips, the cutting won't use any energy trying to heal the leaf, but it still absorbes energy for photosynthesis.
Dip cutting into Clonex
Use a pipette to make new hole in rockwool and put 2 drops of clonex into rockwool.
Place in Rockwool cube.
Firm rockwool around stem of cutting, making sure there is contact between rockwool and cutting.
Mist and place in propagator with holes closed.
Mist twice a day only for 1st 4 days, leaving holes close but "burping" twice a day to let in fresh air.
Let cubes dry a little, but not too dry, to encourage roots.
After 4 days, open vents 1/3 and start misting once a day.
Between 7-10 days I have had roots on every cutting since using this method. Not hundreds of cuttings, probably around 40 or so but I dont have to take millions of cuttings now!
I love the sound of those misters btw.
Green mojo and hope it works out for you.
Peace
W