I did wonder if it were the chlorine in the city water that I was using, but I seem to keep losing them with rain water.
I have been using Miracle Gro potting soil. I did not sterilize it before hand.
This is my fourth year and fifth attempt at growing daisies. I have grown hundreds of tomato and pepper plants in years past, and never had this problem. It seems to be the culprit to killing hundreds of daisy plants that I have grown.
I will bump my Clovis Daisy Project thread if you care to read it.
I think the soil is your problem. Try a seed starting mix instead of potting soil and sprinkle some sphagnum moss over the seeds. Then water from the bottom only with distilled or rain water, don't use so much water that the top gets wet. No fertilizer until they have several sets of leaves. Some plants are terribly hard to start from seed because they are vulnerable to damping off. I just lost half a dozen blue himilayan poppies because of it. I had them in peat pellets that I kept too wet.
I read your original thread. Missed it when you first posted. I'm wondering if they need to have more alkaline conditions. I don't know if you have more seed or can get more and are up to experimenting a bit. Try some in regular seed starting mix and try some in seed starter with a bit of lime mixed in.
I use recycled containers. I put the soil in the container (that has holes in the bottom) and fill to the top. Then pour boiling water into the container. When it cools I plant in it. I put the container in a recycled bag that has holes in it for air movement. As soon as the seeds start to germinate I take off the bag to limit damping off. Put the seeds on the porch when you do this so that there is constant air movement to prevent mold that causes damping off.
I sterilize my soil in the microwave - much easier and less messy than most other ways. However, I only sterilize soil that is being reused. If it comes right out of the bag I don't bother. (I typically use organic seed starting mix.)
I use soil from the yard near where the plants will be planted plus some compost from my pile. Never have sterilized. When they get up to maybe a few inches, I water w/cornmeal juice & never have damping off.