Seems a lot of folks are having issues cloning lately....
IMO- some strains are just not genetically predisposed to cloning.... no matter how great the grow/Mom/Smoke-- they just DO NOT want to clone.
I also think some nutrients used in vegging the Mom may also inhibit rooting...
so unless you change how you grow/feed the mom, you may have trouble.
HOWEVER - some strains will clone at the drop of a hat! I have had some strains so powerful that I had cut off lower branches and stuck all of them in a bubbler-bucket just to pre-sex them, and they rooted!!
IF you are having trouble getting clones to root-- ESPECIALLY in hydro cloners (there is an issue there-- PM me!) or in soil---
Use "Rapid Rooters", Rock-wool or "Root Riots" for best results.
Use a NEW matchstick or toothpick to ensure the hole in the center is open... and soak them for 2-3 hours in pH adjusted water (at 6.2-6.5--like soil).
Add a rooting solution such as KLN or Olivia's if you wish.. before you adjust the pH.
When you take your cuttings- be sure the stem is thick and strong-- a stem that is weak and flimsy will not do well and is more likely to get rot. Have a jar or glass of pH adjusted water WITH YOU when you take your cuttings, and submerge the cut end as soon as you cut it from the Mother Plant!
Be sure each clone has a stem at least 3" long with at least one node that will be inside the grow medium...that is where the roots start.
Cut the end at a 40-degree angle and dip in cloning gel before inserting into the VERY WET rooting medium.
Set the rooting cubes in a shallow waterproof dish with about 1/4 inch of solution in the bottom... this keeps them damp at all times.
If you HAVE one-- add an airstone (attached to an air-pump) to the dish with enough of your pH adjusted solution to cover the stone... this aerated solution will speed your cloning!
IF you have a clear dome use it! (even a large clear glass bowl that covers your plants without touching will work!)
Put a 100w CFL above the cuttings for light.... they don't HAVE to have that much- but we've found they do better with more light.
Change the solution every 5 days...every 2 if not using an airstone.
Make sure your area is about 70f (room temp)... not too hot (or the stems cook) and not TOO cold or they won't root. But do NOT use a rooting mat-- those are for seeds only!
Some cuttings tend to droop for a couple days no matter what method you use... but if wilted- throw them out! NEVER leave a sick clone in with the healthy ones!
You should see roots in a couple weeks!!