Most things root better in moist soil than in water. Roots grow in the dark... and need a certain amount of air to stay healthy.
Try a soft cutting, one that has not turned woody...dip it in a rooting hormone and plant it in sand and keep it moist.
See what happens in a month.
Linda C

I agree with lindac. There are plants that will root in water, but they are in the minority. One more thing you can try in addition to hers is to put your cuttings in a sweat box. If you're just doing one or two plants, you can cut the bottom off a milk jug or 2 liter drink bottle and place it over your potted cutting (leave the lid off). If you're doing a number of cuttings, use a clear plastic rubber-maid box turned upside down. I use them and start a dozen or more plants at a time. Once you stick your cuttings, water the pots thoroughly and let them drain until there's no more water coming out of their drain holes. THEN put them in the sweat box. You should see "fog" on the dome. Put them in a shady spot (porch is good) and you don't have to do anything else to them for several weeks. When you see them making new leaves, they're ready to come out of the box. Give them some half strength fertilizer and you're ready to pot them up or put them in the ground.
I have never tried Scaevola, but would like to. Won't you come back and share how this works for you?