I may be doing something wrong, but I'm mining grade 3 nodes in the Black Shroud which are supposed to be really good for silver ore/sand. So far I've mined 6 nodes but I have yet to see a single ore or bit of sand. My miner is rank 29 and I'm targeting the sweet spot for silver ore every time. I've heard people getting silver 25% of the time, but for some reason that just isn't happening at all for me. Am I doing anything wrong?