Alyssum

I am trying to germinate some Alyssum seeds that I bought from an online specialty store.  They are jeweltoned Alyssum.  Most Alyssum is white or purple; rarely it is yellow.  This Alyssum is supposed to be Wine, Red, Salmon, Lemon, Apricot...

"2946 Aphrodite Mix ( Alyssum )  A mix of the Aphrodite colors. The Aphrodite Series of Alyssum is an exciting new line of colors for Alyssum. Grows only 8 inches tall, and flowers in only 9 weeks. Annual. Excellent basket and container plant.  25 Seeds Per Pack $1.95"
However, whatever I am doing to germinate the seeds is not working.  I have them in a jiffy tray, with soil.  I keep it covered and constantly moist.  I have tried two batches; one in full sun and one under shade cloth and I have not gotten a single plant to germinate.  Any suggestions?