Seeds should be stratified for several months but you can make do with less. But if they were only stratified for 3 weeks or so, that might not be enough. It also takes some time to germinate.
I've had success laying seed on a paper towel, misting the towel until its just moist. Then I fold up the paper towel, put it into a baggie and stick it in the fridge for a couple of months. Its worked very well.