Usual problems are an air bubble, too hot an area, you're not misting, or the air is stagnant.
Here ya go:
The mOSt important thing is how you take that cutting, and how big is it, and where you get it, and have SOME Light on it, and in 4 to 6 days in
the Mistic Cloner, or a bubbler cloner, they root!
I always tell people who start from seed to be sure to take two clones from the bottom of each plant just before putting the plants into flower. These clones should be labeled with the same number as the mother plant from which it was taken, as well as the date it was cut. Keep those clones alive! Take the cuttings from the plants taht gave the biggest buds.
Many growers cut the branch underwater so that no air bubbles will form in the stem of the new cutting. (YOU CUT IT OFF THE PLANT, THEN STICK IT UNDER WATER AND CUT IT AGAIN) If air enters the stem it will prevent the stem from carrying water and the cutting will die. Dipping the cut end of the stem immediately into a rooting gel also solves the air bubble problem. If using a powder the cuttings must be wet so that the powder will adhere. BUT I DO NOT USE JELLS OR POWDERS. NO NEED TO, WITH THE MYSTIC CLONER.
you should select a soft, small branch from the bottom of the plant, one that wouldn't amount to much anyway. If you are planning to keep the plant in the VEG cycle, to continue taking cuttings then you should take cuttings from any shoots that have two or three nodes. I take cuttings that are between two and four inches long, but some people prefer to take cuttings as long as eight inches.
The stem will root quickly if it is still soft and green, not woody. Make an even, diagonal slice through the branch with your clean razor, below the would-be cutting. Strip the bottom leaves off of the cutting, dip it in rooting gel and plant it.
If you make your cut right above a node on the branch then two new branches will sprout out as if it had been pinched. If you continue in this fashion then your mother will produce an exponential number of cuttings every two weeks. You will soon be proudly giving clones away to your growing friends.
The clones must be warm but not scorched or too hot. Direct light will burn them because without roots the stem cannot supply the leaves with enough water to match the leaves' rate of transpiration. Use some light,b ut far away light.
Transpiration is a part of how the plant grows. Water and nutrients travel up the stem from the roots to the leaves, where they are used in photosynthesis. Tiny hairs called stomata sweat out the moisture to allow the stream of nutrients to continue flowing. Wind aids in transpiration by blowing the moisture off the stomata, which is why a very slow fan helps. AND MIST them twice a day with plain water or a WEAK foliage nutrient enriched mist.
Do NOT put a timer on it, run it 24/7.
And there you go!
For visitors here, the Mystic Cloner is a small tank with 18 holes, to root 18 clones FAST. Inside the tank is a MISTER, like a FOGGER or FOGGING devise that creates a steady mist or fog in the tank on the ends of the stems. makes roots in 4 to 6 days! You can make your own with a fogger devise from PetSmart, made for lizzards.