Ok,first off you made 3 mistakes that could be the culprit,the reason clones are cut at a 45 degree angle by some is about surface area,an angled cut has more surface area over a straight cut,the cut is full of disrupted cell structures where new roots form,some growers split the stalk down the middle to get more surface area with disrupted cells,same thing with scraping the branch,when you scrape if you scrape down to the white inner layer thats where the cells that make roots lie,scraping or cutting disrupts & exposes them.
Air embolisms,all branches are hollow like a drinking straw,when you cut the clone from the mother air can enter the stalk via the fresh cut,the air bubble stays trapped at the end of the stalk keeping water from being taken up by the cutting,the cutting starts wilting & dies,this is an embolism.
Clonex,what a fukin rip off,clonex works great but why pay $40 a bottle when you can get the exact same shit in powder form at home depot for $5,any cloning product that has INDOLE-3 BUTRIAC ACID will work as good as clonex,super expensive clonex is nothing more than indole 3,the other ingredients are inert & inactive.
Your light is also fucking you up,even a 300 watt cfl is way too much,light should be very minimul,try using a single 24 watt cfl hanging directly over the dome.
More important than light is warmth,the cuttings will root faster & easier if their kept warm,use a heat mat if the temp inside your clone box is under 78 degrees.
Now to fix your cloning technique.
Get a bowl of room temp water & sissors,cut the cutting from the mother making sure everything else is ready,after you take the cutting submerge the entire cutting in the bowl of water,now recut the stalk approx 1 inch higher,all the while being carefull to keep the stalk submerged while the cut is taking place,now if the cutting decides to suck in air from the cut it takes in water instead.
Many growers do not use this method but they should,even the best cloning technique isnt 100% successfull,when experienced cloners have cuttings die its allways from embolisms within the branch.
After you recut the stalk get it dipped in root agent & inside its cube asap,make sure the medium is moist but not soaking wet,i use ROOT RIOT sponge plugs so i can squeeze any extra water out without fucking up the medium from compression.
Keep the clones in a humidome,remove the lid only when you see the condensation on the lid is not covering a large area,when that happens mist the leaves as well as the underside of the humidome,you shouldnt have to remist but once every 2 to 3 days.
In 7 to 10 days you'll have roots.
One more thing,most new cloners are ascared to take large fat cuttings,they fear faliure as well as loosing a good piece of the plant,then they end up cutting wispy lil ass cuttings that are frail as fuk to start with,learn how to top the plant properly & use fat ass cuttings.