Fountain fills and transparencies

I am using CorelDraw X7. I am having trouble with fountain fills and transparencies.
I design prints for fabrics, which are used to make Alpine Skiing race suits. The printing process is a one where the printer prints dye onto paper and then the paper is pressed at a high temperature and pressure onto the fabric; dye sublimation printing.
I am creating designs and patterns using Corel Draw and using fountain fills or transparencies to blend on colour/layer into another smoothly. I set my fountain steps at 999 (maximum) and also use the smooth button to blend the colours further. The fills and transparencies look great on screen but as soon as they are printed I have lines across the blend. This is especially bad when the contrast between the two colours is great. It does not print as a smooth seamless blend of one colour into another.
Can anyone help me.
Thanks Dave