There are some items (~10) which are ordered two or three weeks ago but I didn't get any earnings so far for them. Why is that happening?
Orders do get canceled, products can become unavailable, and some may take longer than the normal one/two day processing period. I get about the same number of unfulfilled orders as you mentioned almost every quarter.
You don't get any earnings until the product ships. I've seen items not ship for several weeks. The order can get canceled before it ships, too.