Seeing veins is a good sign. When you candled them, did you kind of poke them around a bit? Not seeing movement isn't all that uncommon. However, you should see a little movement if you poke the egg a bit and stir them up...
If they died, I would think the veins would degrade quickly and be hard to see when candling. I would also think it wouldn't take too long for the eggs to start to degrade...