Tea Tree Culture & Cuttings

I have a potted tea tree, now 28 inches tall and looking healthy. I have tried several times to take cuttings (different times of year - with or without rooting hormone), but they always die eventually. That is they stay green for some time but don't set roots and eventually wither. I've used bottom heat, no heat, bright light, a cover for 'micro climate'. I always take the fresh growing tips.
I also bought tea tree seed last year and after good germination I lost half to damp-off, potted the remainder, lost half of that, repotted from cells to 3 1/2 inch pots and lost more. There never seems to be much root.

I wonder if you have a sufficiently acid soil for your tea trees. They like a pH of 4.5 to 7.3 and since grow on humps in swamps in their native habitat, they will do best in constantly moist but well-drained, rich soil in a warm and humid environment. When the environment is not optimal, plants become susceptible to all kinds of opportunistic organisms such as damp off. You might try growing the plants in a porous peat based medium such as pro-mix BX. This will hold a lot of water as well as air and tend to be acid.
You might like to try to use slightly woody cuttings with a heel taken in the summer for making more plants. Dip the heel (obtained by tearing a branch off at its base)in rooting hormone- for semi-ripe cuttings- and plant in moist pro-mix. Water, drain, and cover with a clean plastic bag. Keep in a bright place out of direct sunlight. Keep at a temperature of about 25 degrees Celsius. You could also try layering. Again in the summer, nick the lower bark of a long branch, sprinkle on rooting hormone, press some wet pro-mix around the cut area of the branch, wrap in clean plastic, tie above and below the cut area and keep on until you can see roots through the plastic. You may have to add a bit of water now and again if the branch is unwilling to root in a hurry. Cut off and plant when roots are formed, but wait until spring or summer to do so.