Just reread your earlier post. My guess is many of your seeds washed away. And your temps are maybe a little cool, allowing for slower germination. I'm still a novice, but that's my guess for you.
If your are starting in starter pots like that I would keep them someone a little more protected from the elements, otherwise there's really no benefit to the starter pots. Might as well direct sow. The point of using starter trays is to control the environment for best gemination. If you aren't controlling the environment, why do it? If direct sowing, heavy rain may wash to your seeds away from where you planted them. They'll survive the water, just might not stay put. I actually covered my carrots with a beach umbrella during a heavy rainfall a few days after planting!
