The humidity should be at 60% atleast and a fan shouldnt be blowing on them. First off people claim clones going straight into soil doesnt have a very high success rate anyways so you should try to buy some rockwool cubes and work with those. Secondly you should try to keep the plants as humid as possible but let them breath for a few minutes everyday. Also do you have any opening on the top that your putting over the clones?