2 things I found very important when I take clones. 1) when you cut your clone from the donor leave it long in length. when you ready to stick in RR make your cut to length underwater and hold cut submersed for about 10-15 seconds, that way no sucking of air bubble. 2) Dont use real thick stemmed clones. If the stem is so thick that you can see it is hollow then it most likely wont take. Seems roots dont like to form from a hollow stem. Lastly Dome=humidity