Does Delta Keyer spill suppression do anything?

Hi,

I don't know if it's user error, but when I use the Delta Keyer in the current beta (2) and I switch spill suppresion from none to f.e. burnt I don't see a difference at all. The fringe color sliders do have an effect on the image, but spill supression doesn't seem to do anything for me. Is there something on the other pages that I need to turn on/off to make it work? Adding a matte control and doing spill suppresion there makes a big difference.