I am looking up recipes to start ordering dyi flavoring [tfa] while playing with the calculator on the bottom it has 2 boxes, target vg and target pg. I was planning to order 48mg nic 100% vg I am trying to make my juices as close to max vg as possible 3mg nic. anyway knowing that the flavorings are pg based if i put any thing more than 80% vg and 20% pg in these boxes i get a error message saying pg cant be negative. I dont understand this can some one give me insight.?