Help with greens???

I planted a row of greens (mostly mixed lettuces) and spinach on April 14 and NOTHING has sprouted yet. The seeds were a couple of years old (2006). The temps have been in the 60s and 70s during the day and 40s and 50s at night. The soil drains well, and contains a lot of broken-up straw. I've watered every day that it hasn't rained. The row gets sunlight most of the day. I covered the row with netting to keep away birds and varmints (no sign of either).

Any ideas? Or should I just be patient? :)

thanks!
pam

It's just now about been time but I've found old lettuce seed germinates very poorly.