Sometimes plants that have been rooted in water have a problem transitioning to soil. Why don't you try rooting the cuttings in vermiculite or a seed starting mix. Keep it moist but not wet. You can enclose the cuttings in a baggie and open it occasionally to check for rot and to allow some air to circulate. If you do root them in vermiculite or soil and put them in plastic don't keep them in the sun or they will cook.
Karyn

You may be washing the hormone off the cutting before it has time to get into the cutting (the IBA hormone is not water soluble, but by putting it in water, it may reduce its effectiveness). As above poster mentioned,the transition from water to potting soil can be a problem. The roots formed in water are aclimated to that enviroment, not potting soil.
If you take several cuttings, stick some in sand and others in pearlite...once they have rooted and you compared the roots, they will look very different.