I have had that happen before. I moved them to the bubble cloner and withing a week they had roots. I would go with a bubble cloner. It works like a charm. I am guessing your using peat paletts? There are DIY bubles cloner plans on here and they don't cost allot ot make.
bigworm1922 Reviewed by bigworm1922 on . no roots on clones i used shultz powder root hormone. after 10 day's i was pulling off my humidity lid and accidentally pinch a leaf and the whole clone came out. to my amazement there were no roots and the tip was slightly brown. i have 21 clones and there are no roots on any. WHAT TO DO? Rating: 5