I've had periods of moderate sucess...and then months of failure and then since I changed to doing it this way...I have great sucess, only loosing maybe 2-3 out of 25.

-I use standard 10x20 tray, with humidity dome. Fill it 2-3 inches with peralite. Water the peralite with warm water. Put it one a heating pad. And then use rapid rooter clone plugs per Stinky Attic sticky.

-I open vent 1/4 and don't touch them for 4 days. Then open the vent more and daily take the cover off for a few minutes. After a week I start checking for roots every other day, and if the plugs or peralite dry out I might add more warm water.

When I had my troubles I believe part of the issue was my cloning solution had gone bad. My hydro guy instructed me to keep it in fridge and use only a spoonful at a time. Now I get tiny sized portions from him, they are like $3 each and the size of carmex lip stuff. PERFECT. Sterile and sealed, open the thing. Do two trays, 40-50 clones total, and throw the thing out.