hey man,
you usin a humidity dome?? i was havin crazy troubles gettin em to even stay alive for a couple days, much less root..
well i got a humidity dome, (can jimmy-rig your own for cheap) and placed perlite in the bottom, then put the clones i recently put in rockwool into the dome.
its been about 2 weeks, and no roots yet but there all still alive. thinkin that humidity made a ton of difference, cuz when there at that stage they dont have roots to take in nutrients. that absorb the moisture through the leaves.
hope that helps!