can you clarify some more, by "no weight" do you mean when you pop it on a scale its reading "0"?
420 dubs/nuggets when dried are as light as dried herbs, and just to get an ounce (or a few grams) of a herb, you'll be buying a lot of herb.
So the same is true with your Northern lights - if you are trying to weigh a nugget about half the size of a golf-ball, you'll be lucky if it weighs 0.1oz.
A whole coala when harvested and fresh, may weigh several ounces, but once dried and cured will be 25% of the original weight - maybe less.
A full sandwich bag of your favourite strain, may only an ounce!