Seedling/ Rockwool Failed.. WTF?

I recently had a seedling shrivel up and die on me.. what's the best location to store the seedlings/Rockwool cube until it completely roots before placing it into my hydro system. Would a simple seedling tray/ dome work, because Ive tried the plastic bag/ cup method but the seedlings ending up dying after about 3 days.

dome and tray together. Make sure and soak the rockwool cubes for hours before you use them (in 5.8 ph'd water). And spray the clones a couple times a day for the first week. after that you can take the dome off and spray em a couple times for a couple days then transplant to whatever you use.

I know a great deal of people here really like putting the thing in neoprene in a home made aeroponic cloner. That is another valid option.