Why didn’t my romaine lettuce sprout?

Why didn’t my romaine lettuce sprout?

I planted a row of Parris Island romaine lettuce nearly a month ago. I gave it fifteen days, and it still hadn't sprouted. So I re-seeded, and it still hasn't sprouted. It's from a new packet, bought this spring. The rest of my salad plants (Summercrisp lettuce, Royal Red lettuce, and a spinach I can't remember the name of, along with radishes, beets, and carrots) are growing gangbusters, but the romaine is reluctant to even sprout. I read something about white seed lettuces needing sunlight to sprout, so you should just sprinkle them on the soil and water. Is that what I'm doing wrong? I've been covering them with an 1/8 inch of soil, as per the back of the seed packet. Is it possible that I just got a bad packet? I find it hard to believe that not one seed would sprout, as I've had very good luck with Livingston Seeds. It has been raining a lot lately, as in every day, but there's also been sun and my garden soil drains well. That is, it isn't a mud puddle, but it is wet. And, as mentioned before, everything else is doing great -- no yellow leaves or root rot from the wet. If I don't get something to sprout soon, it's going to be too hot to let it grow. Anybody have some suggestions for something to replace the romaine that is just as delicious? I'm tempted to just plant another row of Summercrisp, but I love dark green lettuces. Would a mesclun mix be a good choice?
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