Have you been using a rooting hormone?
How long are your cuttings?
R U using a fine or coarse sand?
Hans
www.MuscadinesAndMore.com

Here is a link that might be useful: Muscadines And More

Yes, I used a rooting hormone (a gel from a hydroponics place)
The cuttings were about seven inches long, green wood.
I used a sharp sand for kiddie sandboxes.
I tried to be hygienic (sterilizing cutting stuff and such).

I have a bottom heat source, but I don't use it in the summer. In most places the summer heat is hotter than the bottom heat. I don't expect rooting before 60 days for most cuttings. I tent my cuttings to prevent them from drying out and dieing before rooting. Every other day I remove the tent to vent excess moisture, turn the plastic tent inside out and put it back on. Keep them in the shade and don't expect rooting for at least 60 days. Al

What plants are you trying to propagate?

Here in Austin we are trying to get a Food Forest going, and I have several older cultivars I'd like to propagate for it.
Plums, jujubes, blueberries, figs . . .