It could be that the ground is just not warm enough yet for the seed to sprout.
The birdz were splashing around in the puddles I've got standing in theyard.
I think some may have gotten kilt, too...we had that nice sunny weather, but I wasn't around much to water it.
There are a few patches that will likely need fill dirt. I thought it'd grow OK right in front, but now I can see where little rocks are keeping grass from coming up in a few places.