According to Swallowtail Seeds, it wants fairly cool temps to germinate, around 65 deg. Maybe you kept them too warm? And you're not supposed to cover them. I know, basic stuff. Never tried them myself. Or maybe the seeds don't keep well?
Confidence is that feeling you have right before you do something really stupid.
I found allysium seeds 4 pkg.
For $1.00 at the Dollar Store . I mixed the seeds with a cup of flour and sprinkled them in a straight line on the ground. I then lightly sprinkled them with water. With the white flour marking the path it was easy for me to see where and when they germinate. Just like it said on the pkg they germinated in 7to 8 days. It's been about 10 days now and they are now 1/2 inch tall. I live in zone 10a. The day I planted the seeds it was a cool Florida 60'