Dukat Dill sprouted, insulation issues

I seem to be having the same situation with the Dukat Dill as with the tarragon: very sporadic germination.  There´s at least one solid sprout, and a couple of others that have broken the surface, but don´t seem to be doing much.

Dukat Dill, day 16:

Overall, it's not a very impressive germination yield at day 16 considering they were supposed to germinate in 10-14 days.  It's possible that the tray is too warm for them.  The seed packet says a soil temperature of 60-75F is required, and it's possible that since tray 2 is closer to the heater and has the seedling heat mat that it's significantly warmer than 75F.  Maybe I should try re-sowing them in the tray 1 slots where the tarragon didn't germinate. 

The flannel sheet greenhouse insulation seems to be working well now.  I quickly found out that there were consequences to increased insulation, mainly, the heater didn't turn on as frequently.  Ultimately, this was what I wanted, but not at the expense of the plants on the top shelf (farthest from the heater).  Two mornings in a row, the temperature of the top shelf was below 70F. 

My current solution to this problem is to wrap the heater shelf less than the other two.  I also re-taped the edges of the greenhouse structure where the plastic sheets overlap so as to prevent heat and moisture from escaping.  It seems to be working; the temperature of the top shelf was above 70F this morning, which is where I'd like to keep it.