There are always going to be some that don't take, but give them a day or two to perk up. I've rooted several in vermiculite successfully—I think roughly half of them root. If you're using potting soil, make sure the soil is pressed firmly against the stem in the soil and keep it consistently well moistened. You'll do best with two stripped leaf nodes below the soil and about two sets of leaves above. Sorry, I can't remember for certain, but I think tip cuttings work best. Once a few take you'll discover you have more than you want.