sounds like the problem is in the watering....I think Bree is right, water for real. Didn't you and I have a discussion about overwatering? I know when I overwatered some plants I then did the opposite which was not water the next group enough. It does sound like damping off if they are sprouting ok; the tops getting too wet and the roots not wet enough....I'd stop misting and water till they drain; the roots need it.